[4.1.x] Fixed docs build with sphinxcontrib-spelling 7.5.0+.

sphinxcontrib-spelling 7.5.0+ includes captions of figures in the set
of nodes for which the text is checked.

Backport of ac90529cc5 from main

docs/howto/overriding-templates.txt

@@ -112,7 +112,7 @@ For example, you can use this technique to add a custom logo to the
 ``admin/base_site.html`` template:
 
     .. code-block:: html+django
-       :caption: templates/admin/base_site.html
+       :caption: ``templates/admin/base_site.html``
 
         {% extends "admin/base_site.html" %}
 

docs/howto/writing-migrations.txt

@@ -40,7 +40,7 @@ You can also provide hints that will be passed to the :meth:`allow_migrate()`
 method of database routers as ``**hints``:
 
 .. code-block:: python
-    :caption: myapp/dbrouters.py
+    :caption: ``myapp/dbrouters.py``
 
     class MyRouter:
 
@@ -98,7 +98,7 @@ the respective field according to your needs.
   ``AlterField``, and add imports of ``uuid`` and ``models``. For example:
 
   .. code-block:: python
-    :caption: 0006_remove_uuid_null.py
+    :caption: ``0006_remove_uuid_null.py``
 
     # Generated by Django A.B on YYYY-MM-DD HH:MM
     from django.db import migrations, models
@@ -122,7 +122,7 @@ the respective field according to your needs.
   similar to this:
 
   .. code-block:: python
-    :caption: 0004_add_uuid_field.py
+    :caption: ``0004_add_uuid_field.py``
 
     class Migration(migrations.Migration):
 
@@ -149,7 +149,7 @@ the respective field according to your needs.
   of ``uuid``. For example:
 
   .. code-block:: python
-    :caption: 0005_populate_uuid_values.py
+    :caption: ``0005_populate_uuid_values.py``
 
     # Generated by Django A.B on YYYY-MM-DD HH:MM
     from django.db import migrations
@@ -283,7 +283,7 @@ project anywhere without first installing and then uninstalling the old app.
 Here's a sample migration:
 
 .. code-block:: python
-    :caption: myapp/migrations/0124_move_old_app_to_new_app.py
+    :caption: ``myapp/migrations/0124_move_old_app_to_new_app.py``
 
     from django.apps import apps as global_apps
     from django.db import migrations