Update documentation (AppImage#59)

Author: probonopd

README.md

@@ -20,12 +20,13 @@ __Please note:__ This repository is meant to be extremely simple.
 Binaries are provided on GitHub Releases. Should you need to build the runtime locally or on GitHub Codespaces, the following will build the contents of this repository in an Alpine container:
 
 ```
-export ARCHITECTURE=x86_64
-./chroot_build.sh # Or execute the steps in it manually
+export ALPINE_ARCH=x86_64
+./scripts/chroot/chroot_build.sh # Or execute the steps in it manually
 ```
 
 This whole process takes only a few seconds, e.g., on GitHub Codespaces.
 
+See [BUILD.md](BUILD.md) for more information, including on how to build using Docker.
 
 ## Signing