Readme: add nightly testing

Signed-off-by: Vasiliy Doylov <nekocwd@mainlining.org>

README.md

@@ -13,6 +13,20 @@ In the future, it will be replaced by a codec-to-codec connection in the kernel,
 ## How it works:
 ![Diagram](q6meow.svg)
 
+
+## PostmarketOS nightly testing:
+1) [Add my nightly repo](https://git.nekocwd.duckdns.org/Administration/Documentation/src/branch/master/install-nightly-repo.md)
+2) Install package
+  ```
+  sudo apk add q6meowd@nightly
+  ```
+3) Enable demon autostart
+  ```
+  sudo rc-update add q6meowd
+  ```
+4) Reboot
+
+
 ## Usage:
 
 * Start without arguments to parse /etc/conf.d/q6voiced configuration.