Remove Administration pages + Keyword Glossary page (#766)

The Database administration pages have now been migrated to the
Operations Manual.
This PR deletes the pages in the Cypher Manual, leaving only the
administration/index.adoc where a note is posted about content
relocation.
This PR also deletes the keyword glossary page, which was not maintained
and is just a poor substitute for the cheat cheet.

---------

Co-authored-by: Reneta Popova <[email protected]>

Author: JPryce-Aklundh

modules/ROOT/content-nav.adoc

@@ -102,21 +102,6 @@
 ** xref:query-caches/unified-query-caches.adoc[]
 
 * xref:administration/index.adoc[]
-** xref:administration/databases.adoc[]
-** xref:administration/aliases.adoc[]
-** xref:administration/servers.adoc[]
-** xref:administration/access-control/index.adoc[]
-*** xref:administration/access-control/manage-users.adoc[]
-*** xref:administration/access-control/manage-roles.adoc[]
-*** xref:administration/access-control/manage-privileges.adoc[]
-*** xref:administration/access-control/built-in-roles.adoc[]
-*** xref:administration/access-control/privileges-reads.adoc[]
-*** xref:administration/access-control/privileges-writes.adoc[]
-*** xref:administration/access-control/database-administration.adoc[]
-*** xref:administration/access-control/dbms-administration.adoc[]
-*** xref:administration/access-control/load-privileges.adoc[]
-*** xref:administration/access-control/limitations.adoc[]
-*** xref:administration/access-control/privileges-immutable.adoc[]
 
 * xref:syntax/index.adoc[]
 ** xref:syntax/parsing.adoc[]
@@ -128,7 +113,6 @@
 ** xref:syntax/comments.adoc[]
 
 * xref:deprecations-additions-removals-compatibility.adoc[]
-* xref:keyword-glossary.adoc[]
 
 * Appendix
 ** xref:styleguide.adoc[]