Write rst parser for GSL ver 2.4 and 2.5

[masa16]

[0xdevalias]

Is this resolved since the following is merged?

• rst parser and files to support GSL 2.4 to 2.6 #11

[nanobowers]

@0xdevalias I revisited this a couple of years after the PR and in retrospect I'm not sure I did it properly. 🫤 Would be nice to get confirmation from someone running gsl 2.4 .. 2.6 to hear if it works or not.