Documentation: add note about WAL mode with SQLite

docs/setup.md

@@ -713,7 +713,8 @@ Paperless runs on Raspberry Pi. However, some things are rather slow on
 the Pi and configuring some options in paperless can help improve
 performance immensely:
 
--   Stick with SQLite to save some resources.
+-   Stick with SQLite to save some resources. See [troubleshooting](troubleshooting.md#log-reports-creating-paperlesstask-failed)
+    if you encounter issues with SQLite locking.
 -   Consider setting [`PAPERLESS_OCR_PAGES`](configuration.md#PAPERLESS_OCR_PAGES) to 1, so that paperless will
     only OCR the first page of your documents. In most cases, this page
     contains enough information to be able to find it.

docs/troubleshooting.md

@@ -320,7 +320,9 @@ many workers attempting to access the database simultaneously.
 Consider changing to the PostgreSQL database if you will be processing
 many documents at once often. Otherwise, try tweaking the
 [`PAPERLESS_DB_TIMEOUT`](configuration.md#PAPERLESS_DB_TIMEOUT) setting to allow more time for the database to
-unlock. This may have minor performance implications.
+unlock. Additionally, you can change your SQLite database to use ["Write-Ahead Logging"](https://sqlite.org/wal.html).
+These changes may have minor performance implications but can help
+prevent database locking issues.
 
 ## gunicorn fails to start with "is not a valid port number"