add changelog (#129)

source/manual/how-tos/changelog.rst

@@ -0,0 +1,37 @@
+==========
+Changelogs
+==========
+
+OPNsense core offers a changelog of the core and the plugins may offer their own changelog,
+if they are growing rapidly so the changelog does not fit into core anymore.
+
+Core
+====
+
+Core offers a changelog section in the area **System -> Firmware** as an own menu or the dialog will
+automatically open in case of an available update.
+
+To open a changelog manually, you can open the Changelog tab, and click the book:
+
+.. image:: images/changelog_book_icon.png
+
+After opening the changelog, you will get an entry like this one:
+
+.. image:: images/changelog_entry.png
+
+The changelog entries can be found at different places:
+
+* Forum: https://forum.opnsense.org/index.php?board=11.0
+* GitHub: https://github.com/opnsense/changelog/tree/master/doc
+* Blog: https://opnsense.org/blog/
+* Reddit: https://www.reddit.com/r/OPNsenseFirewall/
+
+Plugins
+=======
+
+The plugins changelogs can be found in the plugins section after clicking the info button of the plugin
+(Plugins tab in Firmware).
+
+.. image:: images/changelog_plugins_info_nginx.png
+
+After the description of the software behind the plugin or the plugin itsef, the changelog follows.

source/manual/howtos.rst

@@ -12,6 +12,7 @@ How-tos
    how-tos/bind
    how-tos/c-icap
    how-tos/cachingproxy
+   how-tos/changelog
    how-tos/carp
    how-tos/cellular
    how-tos/clamav