Fix up a couple of references to 'only_if' and change them to 'when'

docsite/latest/rst/playbooks.rst

@@ -430,7 +430,7 @@ inside another.
    this, consider how you can restructure your playbook to be more
    class/role oriented.  This is to say you cannot use a 'fact' to
    decide what include file to use.  All hosts contained within the
-   play are going to get the same tasks.  ('only_if' provides some
+   play are going to get the same tasks.  ('*when*' provides some
    ability for hosts to conditionally skip tasks).
 
 Roles

docsite/latest/rst/playbooks2.rst

@@ -288,7 +288,7 @@ there will be accessible to future tasks::
           action: site_facts
         - action: command echo {{ my_custom_fact_can_be_used_now }}
 
-One common useful trick with only_if is to key off the changed result of a last command.  As an example::
+One common useful trick with *when* is to key off the changed result of a last command.  As an example::
 
     tasks:
         - action: template src=/templates/foo.j2 dest=/etc/foo.conf
@@ -700,7 +700,7 @@ Often in a playbook it may be useful to store the result of a given command in a
 it later.  Use of the command module in this way can in many ways eliminate the need to write site specific facts, for
 instance, you could test for the existance of a particular program.
 
-The 'register' keyword decides what variable to save a result in.  The resulting variables can be used in templates, action lines, or only_if statements.  It looks like this (in an obviously trivial example)::
+The 'register' keyword decides what variable to save a result in.  The resulting variables can be used in templates, action lines, or *when* statements.  It looks like this (in an obviously trivial example)::
 
     - name: test play
       hosts: all