Docs for recipes_only (#4238)

* Docs for recipes_only

* Wording review

Author: AbrilRBS

devops/using_conancenter.rst

@@ -103,6 +103,14 @@ we recommend building your own binary packages from source:
 
 - Read more: :ref:`creating and hosting your own Conan Center binaries <devops_conancenter_hosting_your_own_conancenter_fork>`
 
+If the ``conancenter`` remote is used directly, your organization might require
+that the binaries are built from source, and not downloaded directly from ConanCenter.
+This can exceptionally be achieved with the ``recipes_only`` field
+:ref:`in the remote configuration<reference_config_files_remotes_json>`, but it is
+highly likely that you will also want to build the packages from source, and not
+depend on the recipes and binaries provided by ConanCenter. See the above link
+for more information.
+
 Control and customization
 -------------------------
 It is very common for users of dependencies to require custom changes to external 

reference/config_files/remotes.rst

@@ -35,6 +35,10 @@ The fields for each remote are:
 * ``disabled`` (Optional, ``bool`` value, ``false`` by default): If the remote is enabled or not to be used by commands
   like search, list, download and upload. Notice that a disabled remote can be used to authenticate against it even
   if it's disabled.
+* ``allowed_packages``: (Optional, ``list`` of ``string`` values): List of recipes that are allowed to be
+  downloaded from this remote. If the list is empty or not present, all packages are allowed. Uses fnmatch rules.
+* ``recipes_only``: (Optional, ``bool`` value, ``false`` by default): If true, only recipes will be
+  downloaded from this remote, no binaries will be downloaded.
 
 
 .. seealso::