Added release instruction md file

Author: permutationlock

RELEASE.md

@@ -0,0 +1,29 @@
+# Generating release binaries
+
+The script `release_make.sh` is used to generate all release binaries.
+
+## Prerequisites
+To run the script you will need to be on a POSIX system with
+`make`, `zip`, `tar`, [`zig`][2], and [`emcc`][3] in the `PATH`.
+
+You will also need a [musl libc][1] sysroot. Such a sysroot may easily
+be created by downloading the musl source code and building and
+installing it at a local prefix. The script `musl-sysroot_make.sh` will
+download a musl release using `curl` and create a `musl-sysroot` sub directory
+in the current working directory.
+
+## Running the script
+
+If you have a `musl-sysroot` folder created by `musl-sysroot_make.sh`, then you
+may run
+```Shell
+MUSL_SYSROOT=musl-sysroot ./release_make.sh
+```
+The release binaries and zip files will be in the `build_release`
+directory.
+
+## Cleaning
+
+```Shell
+./release_clean.sh
+```