[bug#43771] [PATCH v2 2/5] doc: Add subheadings in to the Databases section.

[Christopher Baines]

To make it clearer where the relevant documentation for a particular service
starts and ends.

* doc/guix.texi (Database Services): Add subheadings.
---
 doc/guix.texi | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/doc/guix.texi b/doc/guix.texi
index 130985d30f..d6d610acae 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -18178,6 +18178,8 @@ details.
 @cindex SQL
 The @code{(gnu services databases)} module provides the following services.
 
+@subsubheading PostgreSQL
+
 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
        [#:config-file] [#:data-directory ``/var/lib/postgresql/data''] @
        [#:port 5432] [#:locale ``en_US.utf8''] [#:extension-packages '()]
@@ -18243,6 +18245,8 @@ dblink as they are already loadable by postgresql.  
This field is only
 required to add extensions provided by other packages.
 @end deffn
 
+@subsubheading MariaDB/MySQL
+
 @deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]
 Return a service that runs @command{mysqld}, the MySQL or MariaDB
 database server.
@@ -18267,6 +18271,8 @@ TCP port on which the database server listens for 
incoming connections.
 @end table
 @end deftp
 
+@subsubheading Memcached
+
 @defvr {Scheme Variable} memcached-service-type
 This is the service type for the @uref{https://memcached.org/,
 Memcached} service, which provides a distributed in memory cache.  The
@@ -18299,6 +18305,8 @@ Additional command line options to pass to 
@code{memcached}.
 @end table
 @end deftp
 
+@subsubheading MongoDB
+
 @defvr {Scheme Variable} mongodb-service-type
 This is the service type for @uref{https://www.mongodb.com/, MongoDB}.
 The value for the service type is a @code{mongodb-configuration} object.
@@ -18325,6 +18333,8 @@ MongoDB is configured to use through the configuration 
file.
 @end table
 @end deftp
 
+@subsubheading Redis
+
 @defvr {Scheme Variable} redis-service-type
 This is the service type for the @uref{https://redis.io/, Redis}
 key/value store, whose value is a @code{redis-configuration} object.
-- 
2.28.0