Collections docs generation (#59761)

* Build documentation for Ansible-2.10 (formerly known as ACD).

Builds plugin docs from collections whose source is on galaxy

The new command downloads collections from galaxy, then finds the
plugins inside of them to get the documentation for those plugins.

* Update the python syntax checks
  * docs builds can now require python 3.6+.

* Move plugin formatter code out to an external tool, antsibull-docs.
  Collection owners want to be able to extract docs for their own
  websites as well.
* The jinja2 filters, tests, and other support code have moved to antsibull
* Remove document_plugins as that has now been integrated into antsibull-docs

* Cleanup and bugfix to other build script code:
  * The Commands class needed to have its metaclass set for abstractmethod
    to work correctly
  * Fix lint issues in some command plugins

* Add the docs/docsite/rst/collections to .gitignore as
  everything in that directory will be generated so we don't want any of
  it saved in the git repository
* gitignore the build dir and remove edit docs link on module pages

* Add docs/rst/collections as a directory to remove on make clean
* Split the collections docs from the main docs

* remove version and edit on github
* remove version banner for just collections
* clarify examples need collection keyword defined

* Remove references to plugin documentation locations that no longer exist.
  * Perhaps the pages in plugins/*.rst should be deprecated
    altogether and their content moved?
  * If not, perhaps we want to rephrase and link into the collection
    documentation?
  * Or perhaps we want to link to the plugins which are present in
    collections/ansible/builtin?

* Remove PYTHONPATH from the build-ansible calls
  One of the design goals of the build-ansible.py script was for it to
  automatically set its library path to include the checkout of ansible
  and the library of code to implement itself.  Because it automatically
  includes the checkout of ansible, we don't need to set PYTHONPATH in
  the Makefile any longer.

* Create a command to only build ansible-base plugin docs
  * When building docs for devel, only build the ansible-base docs for
    now.  This is because antsibull needs support for building a "devel
    tree" of docs.  This can be changed once that is implemented
  * When building docs for the sanity tests, only build the ansible-base
    plugin docs for now.  Those are the docs which are in this repo so
    that seems appropriate for now.

1 files changed, 2 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
index cdd3941dee..5590928817 100644
--- a/.gitignore
+++ b/.gitignore
@@ -37,6 +37,8 @@ docs/docsite/rst/cli/ansible.rst
 docs/docsite/rst/dev_guide/collections_galaxy_meta.rst
 docs/docsite/rst/dev_guide/testing/sanity/index.rst.new
 docs/docsite/rst/modules/*.rst
+docs/docsite/rst/collections/*.rst
+docs/docsite/rst/collections/*/*.rst
 docs/docsite/rst/playbooks_directives.rst
 docs/docsite/rst/plugins_by_category.rst
 docs/docsite/rst/plugins/*/*.rst