[impressum] Add addon config

- Update mentions to .htconfig.php

impressum/config/impressum.ini.php

@@ -0,0 +1,33 @@
+<?php return <<<INI
+
+; Warning: Don't change this file! It only holds the default config values for this addon.
+; Instead overwrite these config values in config/local.ini.php in your Friendica directory
+
+[impressum]
+; owner (String)
+; This is the Name of the Operator
+owner =
+
+; ownerprofile (String)
+; This is an optional Friendica account where the above owner name will link to
+ownerprofile =
+
+; email (String)
+; A contact email address (optional)
+; Will be displayed slightly obfuscated as name(at)example(dot)com
+email =
+
+; postal (String)
+; Should contain a postal address where you can be reached at (optional)
+postal =
+
+; notes (String)
+; Additional informations that should be displayed in the Impressum block
+notes =
+
+; footer_text (String)
+; Text that will be displayed at the bottom of the pages.
+footer_text =
+
+INI;
+//Keep this line