gh-36229: Fixed grammatical errors at multiple points in English documentation
    
There were various grammatical errors, mostly pertaining to the use of
English articles "a" and "an" with corresponding nouns, all of which
have now exhaustively been fixed.

This also fixes Issue #35642.
This fix makes the documentation in English more readable and improves
developer experience. All the changes for article-noun agreement are in
accordance to American English standards.
I used VSCode's regular expression search to find out all the instances
of erroneous article usage and changed them manually.

Some examples are given below.

`src\sage\schemes\toric\library.py:          * This is an example of an
non-polyhedral fan.`
`src\sage\schemes\hyperelliptic_curves\jacobian_generic.py: An more
extended example, demonstrating arithmetic...
src\sage\rings\number_field\S_unit_solver.py: # Note that l is the an
lower bound on the square of the magnitude...`

The lines above have respectively been changed to:

`src\sage\schemes\toric\library.py:          * This is an example of a
non-polyhedral fan.`
`src\sage\schemes\hyperelliptic_curves\jacobian_generic.py: A more
extended example, demonstrating arithmetic...
src\sage\rings\number_field\S_unit_solver.py: # Note that l is the lower
bound on the square of the magnitude...`

All the changes are only in the documentation/comments at various places
in the project. There were some instances where "an" had to be changed
to "and" or some other word, but they were very few. Most required
changing it to "a" or completely removing the article.

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- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [x] I have updated the documentation accordingly.

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URL: #36229
Reported by: MedantSharan
Reviewer(s): John H. Palmieri, Matthias Köppe, MedantSharan

Author: Release Manager

src/doc/en/developer/coding_in_other.rst

@@ -714,7 +714,7 @@ dumps the user into an Octave interactive shell:
 
             OUTPUT:
 
-            An list x (if it exists) which solves M*x = b
+            A list x (if it exists) which solves M*x = b
 
             EXAMPLES::
 

src/doc/en/developer/review.rst

@@ -134,7 +134,7 @@ the patches have been applied to a given release, the issue would
 remain in limbo.
 
 **No Patch Bombs**: Code that goes into Sage is peer-reviewed. If
-you show up with an 80,000 lines of code bundle that completely
+you show up with 80,000 lines of code bundle that completely
 rips out a subsystem and replaces it with something else, you can
 imagine that the review process will be a little tedious. These
 huge patch bombs are problematic for several reasons and we prefer

src/doc/en/reference/coercion/index.rst

@@ -323,7 +323,7 @@ Methods to implement
   the function is called on the potential codomain.  To indicate that
   there is no coercion from S to R (self), return ``False`` or
   ``None``. This is the default behavior.  If there is a coercion,
-  return ``True`` (in which case an morphism using
+  return ``True`` (in which case a morphism using
   ``R._element_constructor_`` will be created) or an actual
   :class:`Morphism` object with S as the domain and R as the codomain.
 

src/doc/en/thematic_tutorials/explicit_methods_in_number_theory/elliptic_curves.rst

@@ -5,7 +5,7 @@ Cremona's Databases
 -------------------
 
 Cremona's databases of elliptic curves are part of Sage. The curves up
-to conductor 10,000 come standard with Sage, and an there is an optional
+to conductor 10,000 come standard with Sage, and there is an optional
 download to gain access to his complete tables. From a shell, you
 should run ::
 

src/doc/en/thematic_tutorials/numerical_sage/f2py.rst

@@ -204,7 +204,7 @@ you only care about its value before the function is called not
 afterwards. So in the above n tells us how many fiboncci numbers to
 compute we need to specify this as an input, however we don't need
 to get n back as it doesn't contain anything new. Similarly A is
-intent(out) so we don't need A to have an specific value
+intent(out) so we don't need A to have a specific value
 beforehand, we just care about the contents afterwards. F2py
 generates a Python function so you only pass those declared
 intent(in) and supplies empty workspaces for the remaining

src/doc/en/thematic_tutorials/sandpile.rst

@@ -2865,7 +2865,7 @@ SandpileConfig
 
 **\***
 
-   If ``other`` is an configuration, the recurrent element equivalent
+   If ``other`` is a configuration, the recurrent element equivalent
    to the sum.  If ``other`` is an integer, the sum of configuration with
    itself ``other`` times.
 

src/sage/algebras/commutative_dga.py

@@ -3087,7 +3087,7 @@ def is_cohomologous_to(self, other):
 
         def cohomology_class(self):
             r"""
-            Return the cohomology class of an homogeneous cycle, as an element
+            Return the cohomology class of a homogeneous cycle, as an element
             of the corresponding cohomology group.
 
             EXAMPLES::

src/sage/algebras/hecke_algebras/cubic_hecke_algebra.py

@@ -1458,7 +1458,7 @@ def one_basis(self):
     def _an_element_(self):
         r"""
         Overwrite the original method from :mod:`~sage.combinat.free_module`
-        to obtain an more interesting element for ``TestSuite``.
+        to obtain a more interesting element for ``TestSuite``.
 
         EXAMPLES::
 
@@ -2233,7 +2233,7 @@ def _braid_image_by_basis_extension(self, braid_tietze):
             sage: CHA5._basis_extension
             [[4], [-4], [4, 1]]
 
-        case where the braid already has an corresponding basis element::
+        case where the braid already has a corresponding basis element::
 
             sage: CHA5._braid_image_by_basis_extension((1,)) # optional - database_cubic_hecke
             c0

src/sage/algebras/quantum_groups/fock_space.py

@@ -166,7 +166,7 @@ class FockSpace(Parent, UniqueRepresentation):
 
     To go between the canonical basis and the natural basis, for level 1
     Fock space, we follow the LLT algorithm [LLT1996]_. Indeed, we first
-    construct an basis `\{ A(\nu) \}` that is an approximation to the
+    construct a basis `\{ A(\nu) \}` that is an approximation to the
     lower global crystal basis, in the sense that it is bar-invariant,
     and then use Gaussian elimination to construct the lower global
     crystal basis. For higher level Fock space, we follow [Fayers2010]_,

src/sage/calculus/interpolators.pyx

@@ -55,7 +55,7 @@ def polygon_spline(pts):
         ....:                 [lambda x: ps.derivative(real(x))], 0)
         sage: show(m.plot_colored() + m.plot_spiderweb())                               # needs sage.plot
 
-    Polygon approximation of an circle::
+    Polygon approximation of a circle::
 
         sage: pts = [e^(I*t / 25) for t in range(25)]
         sage: ps = polygon_spline(pts)