Document all filter and test plugins (#4597)

* Fix/improve docs.

* Document the a_module test.

* Document the dict filter.

* Linting.

* Add more filter docs.

* More filters.

* Update BOTMETA.

* Add another plugin.

* Fix typos.

* Add explicit entries.

* Fix lookup documentation.

plugins/filter/dict.py

@@ -6,6 +6,60 @@
 from __future__ import absolute_import, division, print_function
 __metaclass__ = type
 
+DOCUMENTATION = '''
+  name: dict
+  short_description: Convert a list of tuples into a dictionary
+  version_added: 3.0.0
+  author: Felix Fontein (@felixfontein)
+  description:
+    - Convert a list of tuples into a dictionary. This is a filter version of the C(dict) function.
+  options:
+    _input:
+      description: A list of tuples (with exactly two elements).
+      type: list
+      elements: tuple
+      required: true
+'''
+
+EXAMPLES = '''
+- name: Convert list of tuples into dictionary
+  ansible.builtin.set_fact:
+    dictionary: "{{ [[1, 2], ['a', 'b']] | community.general.dict }}"
+    # Result is {1: 2, 'a': 'b'}
+
+- name: Create a list of dictionaries with map and the community.general.dict filter
+  ansible.builtin.debug:
+    msg: >-
+      {{ values | map('zip', ['k1', 'k2', 'k3'])
+                | map('map', 'reverse')
+                | map('community.general.dict') }}
+  vars:
+    values:
+      - - foo
+        - 23
+        - a
+      - - bar
+        - 42
+        - b
+  # Produces the following list of dictionaries:
+  #   {
+  #     "k1": "foo",
+  #     "k2": 23,
+  #     "k3": "a"
+  #   },
+  #   {
+  #     "k1": "bar",
+  #     "k2": 42,
+  #     "k3": "b"
+  #   }
+'''
+
+RETURN = '''
+  _value:
+    description: Whether the module or action plugin denoted by the input exists.
+    type: boolean
+'''
+
 
 def dict_filter(sequence):
     '''Convert a list of tuples to a dictionary.