README installation guide is erroneous

The README suggests to use "https://github.com/zig-utils/zig-regex/archive/main.tar.gz" as the url and to then use the hash zig will provide. While this works locally as long as you keep your cache, this will fail on other machines since the hash will change together with changes in the main branch.

Users should target a release.

The problem with that however, is that the new release actually breaks compatibility with the current zig release (0.16.0), because of the usage of @backingInt which only exists on the master branch.

One way that could be described is using protocl git+https to fetch. For example, to get a working version, I use this in my project:

zig fetch --save git+https://github.com/zig-utils/zig-regex/#86159c5b9e0996ce6942b99d4ea76ed6c80a9a24

Because this is a commit still using 0.16.0 and that correctly parses when braces are involved.