collection_requirements: add meta/execution-environments.yml (ansible#871)

* collection_requirements: add requirements.txt and bindep.txt

* Change

* Fix

* Update wrt recent builder docs update

Author: Andersson007

docs/docsite/rst/community/collection_contributors/collection_requirements.rst

@@ -156,6 +156,7 @@ Your collection repository MUST have a ``README.md`` in the root of the collecti
 
 meta/runtime.yml
 ----------------
+
 Example: `meta/runtime.yml <https://github.com/ansible-collections/collection_template/blob/main/meta/runtime.yml>`_
 
 * The ``meta/runtime.yml`` MUST define the minimum version of Ansible which this collection works with.
@@ -165,6 +166,13 @@ Example: `meta/runtime.yml <https://github.com/ansible-collections/collection_te
 
 .. _coll_module-reqs:
 
+meta/execution-environment.yml
+------------------------------
+
+If a collection has controller-side Python package and/or system package requirements, to allow easy `execution environment <https://ansible.readthedocs.io/en/latest/getting_started_ee/index.html>`_ building, they SHOULD be listed in corresponding files under the ``meta`` directory, specified in ``meta/execution-environment.yml``, and `verified <https://ansible.readthedocs.io/projects/builder/en/latest/collection_metadata/#when-installing-collections-using-ansible-galaxy>`_.
+
+See the `Collection-level dependencies guide <https://ansible.readthedocs.io/projects/builder/en/latest/collection_metadata/#collection-level-dependencies>`_ for more information and `collection_template/meta <https://github.com/ansible-collections/collection_template/tree/main/meta>` directory content as an example.
+
 Modules & Plugins
 ------------------