Add installation instructions to readme

README.md

@@ -1,3 +1,15 @@
 # Tusker
 
 Tusker is a WIP iOS app for Mastodon and Pleroma.
+
+## Installing for Development
+
+Xcode 11 is required, macOS Mojave or later should work (only macOS Catalina is regularly tested).
+
+1. Clone the project: `git clone https://git.shadowfacts.net/shadowfacts/Tusker.git`
+2. Change directory into the project: `cd Tusker`
+3. Clone the submodules: `git submodule init && git submodule update`
+4. Open `Tusker.xcworkspace` in Xcode.
+5. Change the code signing identity to your own.
+6. Change the bundle identifier to something unique.
+7. Select a target in the Tusker scheme and build & run.