[FIX] reference/view_architectures: remove outdated and broken link

The external link to `AbstractController` class was broken, both because
the placeholder substitution mechanism doesn't work in included RST
excerpts and because the class has long been removed.

Since it makes little sense to replace the link with another link to
the `useActionLinks` hook in the context of this reference doc, this
commit removes the link altogether, as well as the erroneous mention
of class limitations.

closes odoo/documentation#10733

X-original-commit: e7d2be6366
Signed-off-by: Antoine Vandevenne (anv) <anv@odoo.com>

conf.py

@@ -391,6 +391,9 @@ def setup(app):
     app.add_config_value('is_remote_build', None, 'env')  # Whether the build is remotely deployed
     app.add_config_value('source_read_replace_vals', {}, 'env')
     app.connect('source-read', source_read_replace)
+    # TODO uncomment after moving to >= v7.2.5 to also substitute placeholders in included  files.
+    #  See https://github.com/sphinx-doc/sphinx/commit/ff1831
+    #  app.connect('include-read', source_read_replace)
 
     app.add_lexer('json', JsonLexer)
     app.add_lexer('xml', XmlLexer)