Make the recheck policy more prominently visible

It has been suggested in the Neutron CI meeting to include a section in
the documentation advicing against blind rechecks. It turns out that
such section already exists. What this change does is to move the
section to the first level of the contributors guide, to make it more
visible. This change also improves some wording and adds some examples
of proper recheck comments.

Change-Id: Ib0a00d13a28f98b0a0f26c7233365d04453db4e0

doc/source/contributor/gerrit-recheck.rst

@@ -9,12 +9,14 @@ being tested, while other times the failure can be caused by a previously
 untracked bug. Such failures are usually related to tests that interact with
 a live system, like functional, fullstack and tempest jobs.
 
-Before issuing a recheck on your patch, make sure that the gate failure is not
-caused by your patch. Failed job can be also caused by some infra issue, for
-example unable to fetch things from external resources like git or pip due to
-outage. Such failures outside of OpenStack world are not worth tracking in
-launchpad and you can recheck leaving couple of words what went wrong. Data
-about gate stability is collected and visualized via
+Unnecessary rechecks lead to wasted resources as well as longer result times
+for patches in other projects. As a consequence, before issuing a recheck,
+make sure that the gate failure is not caused by your patch. A failed job can
+also be caused by some infra issue, for example the inability to fetch things
+from external resources like git or pip due to an outage. Such failures outside
+of the OpenStack world are not worth tracking in launchpad and you can recheck
+by leaving a short comment indicating what went wrong. Data about gate
+stability is collected and visualized via
 `Grafana <https://grafana.opendev.org/d/f913631585/neutron-failure-rate>`_.
 
 Please, do not recheck without providing the bug number for the failed job.
@@ -24,3 +26,12 @@ exist yet, create one so other team members can have a look. It helps us
 maintain better visibility of gate failures. You can find how to troubleshoot
 gate failures in the :ref:`Gate Failure Triage <troubleshooting-tempest-jobs>`
 documentation.
+
+Here are some real examples of proper rechecks:
+
+- Spurious issue in other component: **recheck tempest-integrated-storage :
+  intermittent failure nova bug #1836754**
+- Deployment issue on the job: **recheck cinder-plugin-ceph-tempest timed out,
+  errors all over the place**
+- External service failure: **recheck Third party grenade : Failed to retrieve
+  .deb packages**

doc/source/contributor/index.rst

@@ -47,6 +47,14 @@ Neutron Policies
 
    policies/index
 
+Gerrit Rechecks
+---------------
+
+.. toctree::
+   :maxdepth: 2
+
+   gerrit-recheck
+
 Neutron Stadium
 ---------------
 

doc/source/contributor/policies/index.rst

@@ -32,4 +32,3 @@ items.
    code-reviews
    release-checklist
    thirdparty-ci
-   gerrit-recheck