docs/manual: introduce "Integration topics" chapter

We want to add more information in the manual about how a system created
with buildroot works overall. We currently already have a chapter about
SELinux, but we want to add more information like that, e.g. details
about how systemd in Buildroot works.

Create a new chapter "Integration topics" with an introductory blurb,
and move the SELinux topic under it (as a section rather than a
chapter).

"Integration topics" is not the best title, but we couldn't find
anything better.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
[yann.morin.1998@free.fr: remove selinux from main manual.txt]
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

docs/manual/selinux-support.txt → docs/manual/integration-selinux-support.txt

@@ -2,7 +2,7 @@
 // vim: set syntax=asciidoc:
 
 [[selinux]]
-== Using SELinux in Buildroot
+=== Using SELinux in Buildroot
 
 https://selinuxproject.org[SELinux] is a Linux kernel security module
 enforcing access control policies. In addition to the traditional file
@@ -30,7 +30,7 @@ upstream https://github.com/SELinuxProject/refpolicy[refpolicy]
 project, enabled with +BR2_PACKAGE_REFPOLICY+.
 
 [[enabling-selinux]]
-=== Enabling SELinux support
+==== Enabling SELinux support
 
 To have proper support for +SELinux+ in a Buildroot generated system,
 the following configuration options must be enabled:
@@ -42,7 +42,7 @@ In addition, your filesystem image format must support extended
 attributes.
 
 [[selinux-policy-tweaking]]
-=== SELinux policy tweaking
+==== SELinux policy tweaking
 
 The +SELinux refpolicy+ contains modules that can be enabled or
 disabled when being built. Each module provide a number of +SELinux+

docs/manual/integration.txt

@@ -0,0 +1,12 @@
+// -*- mode:doc; -*-
+// vim: set syntax=asciidoc:
+
+[[integration]]
+== Integration topics
+
+This chapter discusses how various things are integrated at system
+level. Buildroot is highly configurable, almost everything discussed
+here can be changed or overridden by xref:rootfs-custom[rootfs overlay
+or custom skeleton] configuration.
+
+include::integration-selinux-support.txt[]

docs/manual/manual.txt

@@ -38,7 +38,7 @@ include::common-usage.txt[]
 
 include::customize.txt[]
 
-include::selinux-support.txt[]
+include::integration.txt[]
 
 include::faq-troubleshooting.txt[]