Tone and style revisions of the runbooks page

Apply tone and style revisions to the runbooks page to bring it
closer to GitLab style.

doc/.vale/gitlab/spelling-exceptions.txt

@@ -201,6 +201,7 @@ namespaced
 namespaces
 Nanoc
 NGINX
+Nurtch
 OAuth
 Okta
 offboarded
@@ -277,6 +278,7 @@ resync
 reverified
 reverifies
 reverify
+Rubix
 runbook
 runbooks
 runit

doc/user/clusters/applications.md

@@ -366,7 +366,7 @@ will also see ready-to-use DevOps Runbooks built with Nurtch's [Rubix library](h
 
 More information on
 creating executable runbooks can be found in [our Runbooks
-documentation](../project/clusters/runbooks/index.md#executable-runbooks). Note that
+documentation](../project/clusters/runbooks/index.md#configure-an-executable-runbook-with-gitlab). Note that
 Ingress must be installed and have an IP address assigned before
 JupyterHub can be installed.