PG HA: Rework headings to get unique links

As the flow of the PG HA documentation needs you to keep in mind several
roles, and visit them at multiple steps of the process, we end up with
mutiple headings called `Consul`, `PostgreSQL`, `Database`, and
`Pgbouncer`.

These headings become HTML anchors so a user can link to a particular
section of the document, but when needing to link to the Post-configure
of Consul you'd end up at the Consul section in user information.

Here we reword the headings.  They are less terse, but it allows for
deep-linking.

https://gitlab.com/gitlab-org/build/team-tasks/issues/30

doc/administration/high_availability/alpha_database.md

@@ -66,7 +66,7 @@ the communication as well as information required for running the service.
 Bellow you will find details on each service and the minimum required
 information you need to provide.
 
-#### Consul
+#### Consul information
 
 When using default setup, minimum configuration requires:
 
@@ -92,7 +92,7 @@ database
   - `/var/opt/gitlab/pgbouncer/pg_auth`: hashed
   - `/var/opt/gitlab/gitlab-consul/.pgpass`: plaintext
 
-#### PostgreSQL
+#### PostgreSQL information
 
 When configuring PostgreSQL, we will set `max_wal_senders` to one more than
 the number of database nodes in the cluster.
@@ -121,7 +121,7 @@ Can be generated with:
     echo -n 'POSTGRESQL_USER_PASSWORDPOSTGRESQL_USERNAME' | md5sum
     ```
 
-#### Pgbouncer
+#### Pgbouncer information
 
 When using default setup, minimum configuration requires:
 
@@ -145,7 +145,7 @@ Few notes on the service itself:
   - `/etc/gitlab/gitlab.rb`: hashed, and in plain text
   - `/var/opt/gitlab/pgbouncer/pg_auth`: hashed
 
-#### Repmgr
+#### Repmgr information
 
 When using default setup, you will only have to prepare the network subnets that will
 be allowed to authenticate with the service.
@@ -170,7 +170,7 @@ When installing the GitLab package, do not supply `EXTERNAL_URL` value.
 
 Each node needs to be configured to run only the services it needs.
 
-### Consul nodes
+### Configuring the Consul nodes
 
 On each Consul node perform the following:
 
@@ -210,7 +210,7 @@ See `START user configuration` section in the next step for required information
 
 After this is completed on each Consul server node, proceed further.
 
-### Database nodes
+### Configuring the Database nodes
 
 On each database node perform the following:
 
@@ -356,7 +356,7 @@ attributes set, but the following need to be set.
 After reconfigure successfully runs, the following steps must be completed to
 get the cluster up and running.
 
-### Consul
+### Consul nodes post-configuration
 
 Verify the nodes are all communicating:
 
@@ -377,7 +377,7 @@ DATABASE_NODE_THREE  XXX.XXX.XXX.YYY:8301  alive   client  0.9.2  2         gitl
 PGBOUNCER_NODE       XXX.XXX.XXX.YYY:8301  alive   client  0.9.0  2         gitlab_consul
 ```
 
-### Database nodes
+### Database nodes post-configuration
 
 #### Primary node
 
@@ -439,7 +439,7 @@ as `MASTER_NODE_NAME`.
 
 Repeat the above steps on all secondary nodes.
 
-### Pgbouncer node
+### Pgbouncer node post-configuration
 
 1. Create a `.pgpass` file user for the `CONSUL_USER` account to be able to
    reload pgbouncer. Confirm `PGBOUNCER_PASSWORD` twice when asked:
@@ -476,7 +476,7 @@ Repeat the above steps on all secondary nodes.
      (2 rows)
      ```
 
-### Application node
+### Application node post-configuration
 
 Ensure that all migrations ran: