manual: tips: document how to build the manual

Signed-off-by: A.R.D. <contact@team-ard.com>
Cc: Willy Lambert <lambert.willy@gmail.com>
Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

docs/manual/make-tips.txt

@@ -54,6 +54,23 @@ and target trees, the images and the toolchain):
  $ make clean
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+.Generating the manual:
+
+The present manual sources are located in the 'docs/manual' directory.
+To generate the manual:
+
+---------------------------------
+ $ make manual-clean
+ $ make manual
+---------------------------------
+
+The manual outputs will be generated in 'output/docs/manual'.
+
+.Notes
+- +asciidoc+ is required to build the documentation (see:
+  xref:requirement-optional[]).
+- There is a known issue that you can't build it under Debian Squeeze.
+
 To delete all build products as well as the configuration:
 
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