Add help text for HTTP user/pass

Add help text for the HTTP password option to all example configs,
since the issue is not obvious, especially give the current
failure mode of a traceback in JSON parsing code.
Add a direct link to the appropriate openstack setting page.

Change-Id: I2ccc723258c502221beb052b3a42b13085a2af7e

examples/minimal-gertty.yaml

@@ -5,5 +5,6 @@ servers:
   - name: CHANGEME
     url: https://CHANGEME.example.org/
     username: CHANGEME
+    # Set corresponding HTTP password in gerrit settings
     password: CHANGEME
     git-root: ~/git/

examples/openstack-gertty.yaml

@@ -8,9 +8,8 @@ servers:
     url: https://review.openstack.org/
     # Your gerrit username.
     username: CHANGEME
-    # Your HTTP Password for gerrit. Go to the "HTTP Password" section in your
+    # Set password at https://review.openstack.org/#/settings/http-password
-    # account settings to generate/retrieve this password.  It is *not* your
+    # Note this is not your launchpad password.
-    # launchpad password.
     password: CHANGEME
     git-root: ~/git/
 

examples/reference-gertty.yaml

@@ -9,6 +9,8 @@ servers:
   - name: CHANGEME
     url: https://CHANGEME.example.org/
     username: CHANGEME
+    # Your HTTP Password for gerrit. Go to the "HTTP Password" section in your
+    # account settings to generate/retrieve this password.
     password: CHANGEME
     git_root: ~/git/