docs: Migrate remaining content to markdown

By stopping using gtk-doc annotations

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3489>

src/compositor/meta-multi-texture.c

@@ -198,7 +198,7 @@ meta_multi_texture_class_init (MetaMultiTextureClass *klass)
  * @n_planes: The number of planes
  *
  * Creates a #MetaMultiTexture with the given @format. Each of the
- * #CoglTexture<!-- -->s represents a plane.
+ * `CoglTexture`s represents a plane.
  *
  * Returns: (transfer full): A new #MetaMultiTexture. Use g_object_unref() when
  * you're done with it.

src/tests/clutter-test-utils.c

@@ -233,7 +233,7 @@ clutter_test_add_data_full (const char     *test_path,
  * The typical test suite is composed of a list of functions
  * called by clutter_test_run(), for instance:
  *
- * |[
+ * ```c
  * static void unit_foo (void) { ... }
  *
  * static void unit_bar (void) { ... }
@@ -251,7 +251,7 @@ clutter_test_add_data_full (const char     *test_path,
  *
  *   return clutter_test_run ();
  * }
- * ]|
+ * ```
  *
  * Return value: the exit code for the test suite
  */

src/tests/clutter-test-utils.h

@@ -51,16 +51,16 @@ G_BEGIN_DECLS
  *
  * Defines the entry point and initializes a Clutter test unit, e.g.:
  *
- * |[
+ * ```
  * CLUTTER_TEST_SUITE (
  *   CLUTTER_TEST_UNIT ("/foobarize", foobarize)
  *   CLUTTER_TEST_UNIT ("/bar-enabled", bar_enabled)
  * )
- * ]|
+ * ```
  *
  * Expands to:
  *
- * |[
+ * ```c
  * int
  * main (int   argc,
  *       char *argv[])
@@ -72,7 +72,7 @@ G_BEGIN_DECLS
  *
  *   return clutter_test_run ();
  * }
- * ]|
+ * ```
  */
 #define CLUTTER_TEST_SUITE(units) \
 int \