mysql: add elements for list params to the modules' documentation (#63187)

lib/ansible/modules/database/mysql/mysql_db.py

@@ -28,6 +28,7 @@ options:
       - if name=all Works like --all-databases option for mysqldump (Added in 2.0).
     required: true
     type: list
+    elements: str
     aliases: [ db ]
   state:
     description:

lib/ansible/modules/database/mysql/mysql_info.py

@@ -32,6 +32,7 @@ options:
     - If you pass including and excluding values to the filter, for example, I(filter=!settings,version),
       the excluding values, C(!settings) in this case, will be ignored.
     type: list
+    elements: str
   login_db:
     description:
     - Database name to connect to.