Add reference to tippin.me links

.github/FUNDING.yml

@@ -4,4 +4,4 @@ custom:
     - 'https://blockstream.info/address/1LukeQU5jwebXbMLDVydeH4vFSobRV9rkj'
     - 'https://blockstream.info/address/3Luke2qRn5iLj4NiFrvLBu2jaEj7JeMR6w'
     - 'https://blockstream.info/address/bc1qlukeyq0c69v97uss68fet26kjkcsrymd2kv6d4'
-    - 'https://tippin.me/@lukechilds'
+    - 'https://tippin.me/@lukechilds?refurl=github.com/lukechilds/dockerpi'

README.md

@@ -9,7 +9,7 @@
 [![Docker Image Size](https://badgen.net/docker/size/lukechilds/dockerpi/latest/amd64?icon=docker&label=lukechilds/dockerpi)](https://hub.docker.com/r/lukechilds/dockerpi/tags)
 [![GitHub Donate](https://badgen.net/badge/GitHub/Sponsor/D959A7?icon=github)](https://github.com/sponsors/lukechilds)
 [![Bitcoin Donate](https://badgen.net/badge/Bitcoin/Donate/F19537?icon=bitcoin)](https://blockstream.info/address/3Luke2qRn5iLj4NiFrvLBu2jaEj7JeMR6w)
-[![Lightning Donate](https://badgen.net/badge/Lightning/Donate/F6BC41?icon=bitcoin-lightning)](https://tippin.me/@lukechilds)
+[![Lightning Donate](https://badgen.net/badge/Lightning/Donate/F6BC41?icon=bitcoin-lightning)](https://tippin.me/@lukechilds?refurl=github.com/lukechilds/dockerpi)
 
 > A Virtualised Raspberry Pi inside a Docker image