more documentation

docs/faq.rst

@@ -19,4 +19,31 @@ is
 
     Dont mess with this folder. Don't change permissions and don't move
     files around manually. This folder is meant to be entirely managed by docker
-    and paperless.
+    and paperless.
+
+**Q:** *Will paperless-ng run on Raspberry Pi?*
+
+**A:** The short answer is yes. The long answer is that certain parts of
+Paperless will run very slow, such as the tesseract OCR. On Rasperry Pi,
+try to OCR documents before feeding them into paperless so that paperless can
+reuse the text. The web interface should be alot snappier, since it runs
+in your browser and paperless has to do much less work to serve the data.
+
+**Q:** *How do I install paperless-ng on Raspberry Pi?*
+
+**A:** There is not docker image for ARM available. If you know how to build
+that automatically, I'm all ears. For now, you have to grab the latest release
+archive from the project page and build the image yourself. The release comes
+with the front end already compiled, so you don't have to do this on the Pi.
+
+You may encounter some issues during the build:
+
+.. code:: shell-session
+
+    W: GPG error: http://ports.ubuntu.com/ubuntu-ports focal InRelease: At least one invalid signature was encountered.
+    E: The repository 'http://ports.ubuntu.com/ubuntu-ports focal InRelease' is not signed.
+    N: Updating from such a repository can't be done securely, and is therefore disabled by default.
+    N: See apt-secure(8) manpage for repository creation and user configuration details.
+
+If this happens, look at `this thread <https://askubuntu.com/questions/1263284/>`:_.
+You will need to update docker to the latest version to fix this issue.