multiple modules: fixed markups in doc (#5227) (#5233)

(cherry picked from commit 6e011f00f4)

Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

plugins/modules/system/dconf.py

@@ -34,7 +34,7 @@ notes:
   - Keep in mind that the C(dconf) CLI tool, which this module wraps around,
     utilises an unusual syntax for the values (GVariant). For example, if you
     wanted to provide a string value, the correct syntax would be
-    C(value="'myvalue'") - with single quotes as part of the Ansible parameter
+    I(value="'myvalue'") - with single quotes as part of the Ansible parameter
     value.
   - When using loops in combination with a value like
     :code:`"[('xkb', 'us'), ('xkb', 'se')]"`, you need to be aware of possible

plugins/modules/system/open_iscsi.py

@@ -78,7 +78,7 @@ options:
         - Whether the list of target nodes on the portal should be
           (re)discovered and added to the persistent iSCSI database.
         - Keep in mind that C(iscsiadm) discovery resets configuration, like C(node.startup)
-          to manual, hence combined with C(auto_node_startup=true) will always return
+          to manual, hence combined with I(auto_node_startup=true) will always return
           a changed state.
         type: bool
         default: false

plugins/modules/system/osx_defaults.py

@@ -51,7 +51,7 @@ options:
   value:
     description:
       - The value to write.
-      - Only required when C(state=present).
+      - Only required when I(state=present).
     type: raw
   state:
     description: