Fix gerrit connection references

Add a missing colon to the example pipeline configuration, and
use 'my_gerrit' for the connection name in the quick start to
make it more clear that it is modifiable.

Change-Id: I4f8de7c8e8df8e810f334e2440f4e6590ddd3883

doc/source/admin/quick-start.rst

@@ -66,7 +66,7 @@ service in Zuul, and a connection to Gerrit.
     [gearman]
     server=127.0.0.1
 
-    [connection gerrit]
+    [connection my_gerrit]
     driver=gerrit
     server=git.example.com
     port=29418
@@ -84,7 +84,7 @@ the *example-project* project:
     - tenant:
         name: example-tenant
         source:
-          gerrit:
+          my_gerrit:
             untrusted-projects:
               - example-project
 

doc/source/user/config.rst

@@ -123,7 +123,7 @@ success, the pipeline reports back to Gerrit with ``Verified`` vote of
          my_gerrit:
            Verified: 1
        failure:
-         my_gerrit
+         my_gerrit:
            Verified: -1
 
 .. TODO: See TODO for more annotated examples of common pipeline configurations.