Remove old versionadded notes

A step has been added to the release process notes to do this for future
releases as well.

https://github.com/torchbox/wagtail/wiki/Creating-a-new-Wagtail-release

docs/advanced_topics/customisation/page_editing_interface.rst

@@ -6,8 +6,6 @@ Customising the editing interface
 Customising the tabbed interface
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-.. versionadded:: 1.0
-
 As standard, Wagtail organises panels for pages into three tabs: 'Content', 'Promote' and 'Settings'. For snippets Wagtail puts all panels into one page. Depending on the requirements of your site, you may wish to customise this for specific page types or snippets - for example, adding an additional tab for sidebar content. This can be done by specifying an ``edit_handler`` attribute on the page or snippet model. For example:
 
 .. code-block:: python

docs/reference/contrib/api/usage.rst

@@ -293,8 +293,6 @@ For example, to get all the pages that are direct children of page 7.
 
 **descendant_of**
 
-.. versionadded:: 1.1
-
 Filters the listing to only include descendants of the specified page.
 
 For example, to get all pages underneath the homepage:

docs/reference/hooks.rst

@@ -69,8 +69,6 @@ Hooks for building new areas of the admin interface (alongside pages, images, do
 ``construct_homepage_summary_items``
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-  .. versionadded:: 1.0
-
   Add or remove items from the 'site summary' bar on the admin homepage (which shows the number of pages and other object that exist on the site). The callable passed into this hook should take a ``request`` object and a list of ``SummaryItem`` objects to be modified as required. These objects have a ``render()`` method, which returns an HTML string, and an ``order`` property, which is an integer that specifies the order in which the items will appear.
 
 

docs/reference/management_commands.rst

@@ -70,9 +70,6 @@ The search may not return any results while this command is running, so avoid ru
 Specifying which backend to update
 ``````````````````````````````````
 
-.. versionadded:: 0.7
-
-
 By default, ``update_index`` will rebuild all the search indexes listed in ``WAGTAILSEARCH_BACKENDS``.
 
 If you have multiple backends and would only like to update one of them, you can use the ``--backend`` option.
@@ -87,8 +84,6 @@ For example, to update just the default backend:
 Indexing the schema only
 ````````````````````````
 
-.. versionadded:: 1.5
-
 You can prevent the ``update_index`` command from indexing any data by using the ``--schema-only`` option:
 
 .. code-block:: console

docs/topics/search/searching.rst

@@ -102,8 +102,6 @@ Changing search behaviour
 Search operator
 ^^^^^^^^^^^^^^^
 
-.. versionadded:: 1.2
-
 The search operator specifies how search should behave when the user has typed in multiple search terms. There are two possible values:
 
  - "or" - The results must match at least one term (default for Elasticsearch)
@@ -151,8 +149,6 @@ For page, image and document models, the ``operator`` keyword argument is also s
 Custom ordering
 ^^^^^^^^^^^^^^^
 
-.. versionadded:: 1.2
-
 By default, search results are ordered by relevance, if the backend supports it. To preserve the QuerySet's existing ordering, the ``order_by_relevance`` keyword argument needs to be set to ``False`` on the ``search()`` method.
 
 For example: