Update documentation.

Refs #5795

AUTHORS

@@ -1 +1,11 @@
-Icinga Development Team <info@icinga.org>
+Bernd Erk <bernd.erk@icinga.org>
+Carlos Cesario <carloscesario@gmail.com>
+Gerd von Egidy <gerd@egidy.de>
+Gunnar Beutner <gunnar.beutner@netways.de>
+Johannes Meyer <johannes.meyer@netways.de>
+Markus Frosch <markus@lazyfrosch.de>
+Michael Friedrich <michael.friedrich@netways.de>
+Pall Sigurdsson <palli-github@minor.is>
+Paul Richards <paul@minimoo.org>
+Ricardo Bartels <ricardo@bitchbrothers.com>
+Wolfgang Nieder <wnd@gmx.net>

INSTALL

@@ -70,10 +70,18 @@ $ git status
 
 Here's a short check-list for releases:
 
+* Update the .mailmap and AUTHORS files
+    $ git log --use-mailmap | grep ^Author: | cut -f2- -d' ' | sort | uniq > AUTHORS
 * Bump the version in icinga2.spec.
 * Update the ChangeLog and doc/1-about.md files.
 * Commit these changes to the "next" branch and create a signed tag (tags/v<VERSION>).
+    $ git commit -v -a -m "Release version <VERSION>."
+    $ git tag -u EE8E0720 -m "Version <VERSION>" v<VERSION>
+    $ git push --tags
 * Merge the "next" branch into the "master" branch (using --ff-only).
+    $ git checkout master
+    $ git merge --ff-only next
+    $ git push origin master
 * Bump the version to "v<NEXT-VERSION>-dev" and commit this change to the "next" branch.
 
 Note: CMake determines the Icinga 2 version number using "git describe" if the
@@ -112,6 +120,7 @@ variables are supported:
 - ICINGA2_USER: The user Icinga 2 should run as; defaults to "icinga"
 - ICINGA2_GROUP: The group Icinga 2 should run as; defaults to "icinga"
 - ICINGA2_COMMAND_USER: The command user Icinga 2 should use; defaults to "icinga"
+- ICINGA2_GIT_VERSION_INFO: Whether to use Git to determine the version number; defaults to "ON"
 - ICINGA2_COMMAND_GROUP: The command group Icinga 2 should use; default to "icingacmd"
 - CMAKE_INSTALL_SYSCONFDIR: The configuration directory; defaults to CMAKE_INSTALL_PREFIX/etc
 - CMAKE_INSTALL_LOCALSTATEDIR: The state directory; defaults to CMAKE_INSTALL_PREFIX/var