Fix RST formatting

Remove whitespaces from build-python-release which make
the sphinx display as "** Role Variable
**" instead of bold "Role Variables".

Fix buildset-artifacts-location to display items as list.

Fix stage-output to display the example as example - and not wrap
around.

Change-Id: I8da3ec0c507d26f47ee9bb71dc9d1b3ed9ca23a5

roles/build-python-release/README.rst

@@ -1,6 +1,6 @@
 Build sdist and wheel for Python projects.
 
-** Role Variables **
+**Role Variables**
 
 .. zuul:rolevar:: release_python
    :default: python

roles/buildset-artifacts-location/README.rst

@@ -4,11 +4,13 @@ When a 'buildset' directory exists in the job logs, then use
 zuul_return to set buildset_artifacts_url for children jobs.
 
 rpm-build job:
+
 * Create a repository
 * Fetch the repository to "{{ zuul.executor.log_root }}/buildset"
 * Use the buildset-artifacts-location role
 
 rpm-test jobs:
+
 * Install "{{ buildset_artficats_url }}" yum repository
 * Run integration tests
 

roles/stage-output/README.rst

@@ -40,7 +40,7 @@ intended to be used before output fetching in a base job's post-playbook.
    `zuul_copy_output` and it won't be applied to files contained in
    folders listed in `zuul_copy_output`.
 
-   Example:
+   Example::
 
      extensions_to_txt:
        conf: True