Add documentation on dict2items (ansible#38375)

dict2items is worth mentioning in the filters and loops pages
(the latter as it's useful to replace `with_dict`)

Update some nearby broken links

docs/docsite/rst/user_guide/playbooks_filters.rst

@@ -161,6 +161,31 @@ To get the symmetric difference of 2 lists (items exclusive to each list)::
     {{ list1 | symmetric_difference(list2) }}
 
 
+.. _dict_filter:
+
+Dict Filter
+```````````
+
+.. versionadded:: 2.6
+
+
+To turn a dictionary into a list of items, suitable for looping, use `dict2items`::
+
+    {{ dict | dict2items }}
+
+Which turns::
+
+    tags:
+      Application: payment
+      Environment: dev
+
+into::
+
+    - key: Application
+      value: payment
+    - key: Environment
+      value: dev
+
 .. _random_filter:
 
 Random Number Filter

docs/docsite/rst/user_guide/playbooks_loops.rst

@@ -72,9 +72,24 @@ If you have a list of hashes, you can reference subkeys using things like::
         - { name: 'testuser1', groups: 'wheel' }
         - { name: 'testuser2', groups: 'root' }
 
-Also be aware that when combining :ref:`when: playbooks_conditionals` with a loop, the ``when:`` statement is processed separately for each item.
+Also be aware that when combining :doc:`playbooks_conditionals` with a loop, the ``when:`` statement is processed separately for each item.
 See :ref:`the_when_statement` for an example.
 
+To loop over a dict, use the ``dict2items`` :ref:`dict_filter`::
+
+    - name: create a tag dictionary of non-empty tags
+      set_fact:
+        tags_dict: "{{ (tags_dict|default({}))|combine({item.key: item.value}) }}"
+      with_items: "{{ tags|dict2items }}"
+      vars:
+        tags:
+          Environment: dev
+          Application: payment
+          Another: "{{ doesnotexist|default() }}"
+      when: item.value != ""
+
+Here, we don't want to set empty tags, so we create a dictionary containing only non-empty tags.
+
 
 .. _complex_loops: