docs: Fix schedule documentation (#15972)

With the "recent" changes making the lookup plugin `awx.awx.schedule_rrule` and
`awx.awx.schedule_rruleset` returning a list instead of string (see #15625), the
returned list (which will *always* carry only 1 item) needs to be transformed
to a string either adding `| join` or `| first`. I found `first` to be more
fitting as the list will *always* return a list with 1 item.

Additionally, the documentation that references `awx.awx.schedule_rruleset`
in the `awx.awx.schedule` module was wrong, which is also fixed by this PR.

Signed-off-by: Steffen Scheib <sscheib@redhat.com>
Co-authored-by: Steffen Scheib <steffen@scheib.me>

awx_collection/plugins/modules/schedule.py

@@ -166,7 +166,7 @@ EXAMPLES = '''
     name: "{{ sched1 }}"
     state: present
     unified_job_template: "Demo Job Template"
-    rrule: "{{ query('awx.awx.schedule_rrule', 'week', start_date='2019-12-19 13:05:51') }}"
+    rrule: "{{ query('awx.awx.schedule_rrule', 'week', start_date='2019-12-19 13:05:51') | first }}"
   register: result
 
 - name: Build a complex schedule for every day except sunday using the rruleset plugin
@@ -174,14 +174,14 @@ EXAMPLES = '''
     name: "{{ sched1 }}"
     state: present
     unified_job_template: "Demo Job Template"
-    rrule: "{{ query(awx.awx.schedule_rruleset, '2022-04-30 10:30:45', rules=rrules, timezone='UTC' ) }}"
+    rrule: "{{ query(awx.awx.schedule_rruleset, '2022-04-30 10:30:45', rules=rrules, timezone='UTC' ) | first }}"
   vars:
     rrules:
       - frequency: 'day'
-        every: 1
+        interval: 1
       - frequency: 'day'
-        every: 1
-        on_days: 'sunday'
+        interval: 1
+        byweekday: 'sunday'
         include: false
 
 - name: Delete 'my_schedule' schedule for my_workflow