add riseup-vpn submodule

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "pkg/riseup-vpn"]
+	path = pkg/riseup-vpn
+	url = https://aur.archlinux.org/riseup-vpn.git

README.md

@@ -1,12 +1,26 @@
 # My personalized Arch Linux packages
 
+## Submodules
+
+There are several AUR packages added as submodules inside [pkg](pkg):
+
+```shell
+git submodule add "https://aur.archlinux.org/riseup-vpn.git" pkg/riseup-vpn
+```
+
+To update all submodules, run
+
+```shell
+git submodule update --remote
+```
+
 ## Build packages from source
 
 Fork this repository.
 
 Then and adjust the following files:
 * [pkg/de-p1st-repo/arch-repo.cfg](pkg/de-p1st-repo/arch-repo.cfg)
-  * For your build-machine, adjust section `LOCAL MACHINE CONFIGURATION`: Add absolute path of folder [./out](./out) to array `LOCAL_PKG_DIRS`
+  * For your build-machine, adjust section `LOCAL MACHINE CONFIGURATION`: Add absolute path of folder [build-pkg/out](build-pkg/out) to array `LOCAL_PKG_DIRS`
     as the build packages will be stored there.
   * For your mirror-server, adjust section `REMOTE MIRROR SERVER CONFIGURATION` accordingly.
 * [pkg/de-p1st-pacman/pacman.d/de-p1st](pkg/de-p1st-pacman/pacman.d/de-p1st)

pkg/riseup-vpn

@@ -0,0 +1 @@
+Subproject commit 9cb290a4f5a6148c4db3687ec62898da2ce815d7