update requirements and links in INSTALL.TXT

- add mariadb and sqlite to requirements
- add link to github
- several small changes

INSTALL.TXT

@@ -5,12 +5,16 @@
 # Licensed under GPL for more info check GPL-LICENSE.TXT
 #
 
-REQUIRED!!
-----------
-- You are using Postfix 2.0 or higher.
-- You are using Apache 1.3.27 / Lighttpd 1.3.15 or higher.
-- You are using PHP 5.1.2 or higher.
-- You are using MySQL 3.23 or higher (5.x recommended) OR PostgreSQL 7.4 (or higher)
+REQUIREMENTS
+------------
+- Postfix 2.0 or higher.
+- Apache 1.3.27 / Lighttpd 1.3.15 or higher.
+- PHP 5.1.2 or higher.
+- one of the following databases:
+  - MySQL 3.23 or higher (5.x recommended)
+  - MariaDB (counts as MySQL ;-)
+  - PostgreSQL 7.4 (or higher)
+  - SQLite 3.12 (or higher)
 
 
 READ THIS FIRST!
@@ -36,11 +40,14 @@ DOCUMENTS/ folder.
 
 1. Unarchive new Postfix Admin
 ------------------------------
+
 Make sure that you are in your WWW directory and then unarchive the
 Postfix Admin archive (whatever the filename is):
 
   $ tar -zxvf postfixadmin-$version.tgz
 
+(if you installed PostfixAdmin as RPM or DEB package, you can obviously skip this step.)
+
 
 2. Setup a Database
 -------------------
@@ -97,7 +104,7 @@ $CONF['configured'] = true;
 
 
 PostfixAdmin does not require write access to any files except the templates_c 
-directory (smarty cache). You can therefore leave the files owned as root (or
+directory (smarty cache). You can therefore leave the files owned by root (or
 another user); as long as the web server user (e.g. www-data) can read them, it
 will be fine.
 For templates_c/, allow write access (only) for the web server user (e. g. www-data).
@@ -151,9 +158,11 @@ You'll need to enable the xmlrpc link (see config.inc.php)
 
 8. More information
 -------------------
-As of March 2007, PostfixAdmin moved to SourceForge.  For the
-forum posts and source updates, see:
 
-https://sourceforge.net/projects/postfixadmin
+PostfixAdmin is hosted on SourceForge. For the forum posts and source updates, see:
+    https://sourceforge.net/projects/postfixadmin
+
+The code and issue tracker is on GitHub:
+    https://github.com/postfixadmin/postfixadmin
 
 There is also #postfixadmin on irc.freenode.net.