src/common/header: Fix URL (MR 68)

The previous commit made a mistake in the URL, fix it.

Fixes 2266d7e4
[ci:skip-build]: already built successfully in CI

src/common/header.css

@@ -6,7 +6,7 @@
  * | | | | | | (_) | |_) | | |  __/_____| (_| (_) | | | |  _| | (_| |
  * |_| |_| |_|\___/|_.__/|_|_|\___|      \___\___/|_| |_|_| |_|\__, |
  * mobile-config-firefox                                        |___/
- * https://gitlab.postmarketos.org/mobile-config-firefox/
+ * https://gitlab.postmarketos.org/postmarketOS/mobile-config-firefox/
  *
  * WARNING: DO NOT EDIT THE COPY OF THIS FILE LOCATED IN YOUR USER PROFILE!
  *