doc: Fix code fences in gix-merge ConflictStyle and Driver

They are not Rust code (they are text with conflict markers and a
shell command, respectively) and they are not intended as doctests,
but the absence of anything on the opening line caused them to be
taken as doctests, so `cargo test --workspace --doc` would fail
with parsing errors.

(Doctests for all crates have not always been run automatically on
CI, so this was not caught when these documentation comments were
introduced in GitoxideLabs#1585.)

Author: EliahKagan

gix-merge/src/blob/builtin_driver/text/mod.rs

@@ -8,20 +8,21 @@ pub enum ConflictStyle {
     /// Only show the zealously minified conflicting lines of the local changes and the incoming (other) changes,
     /// hiding the base version entirely.
     ///
-    /// ```
+    /// ```text
     /// line1-changed-by-both
     /// <<<<<<< local
     /// line2-to-be-changed-in-incoming
     /// =======
     /// line2-changed
     /// >>>>>>> incoming
-    ///```
+    /// ```
     #[default]
     Merge,
     /// Show non-minimized hunks of local changes, the base, and the incoming (other) changes.
     ///
     /// This mode does not hide any information.
-    /// ```
+    ///
+    /// ```text
     /// <<<<<<< local
     /// line1-changed-by-both
     /// line2-to-be-changed-in-incoming
@@ -32,12 +33,12 @@ pub enum ConflictStyle {
     /// line1-changed-by-both
     /// line2-changed
     /// >>>>>>> incoming
-    ///```
+    /// ```
     Diff3,
     /// Like [`Diff3](Self::Diff3), but will show *minimized* hunks of local change and the incoming (other) changes,
     /// as well as non-minimized hunks of the base.
     ///
-    /// ```
+    /// ```text
     /// line1-changed-by-both
     /// <<<<<<< local
     /// line2-to-be-changed-in-incoming

gix-merge/src/blob/mod.rs

@@ -96,7 +96,7 @@ pub struct Driver {
     ///
     /// A typical invocation with all arguments substituted could then look like this:
     ///
-    /// ```
+    /// ```sh
     /// <driver-program> .merge_file_nR2Qs1 .merge_file_WYXCJe .merge_file_UWbzrm 7 file e2a2970 HEAD feature
     /// ```
     ///