website: “provides a binary suitable as /bin/sh” could use clarification

The website currently says “provides a binary suitable as `/bin/sh`”; this could use clarification.

I don’t doubt that, given the code is completed and relevant bugs are fixed, `mrsh` can be used as `/bin/sh` on systems where a POSIX shell suffices.

However, a significant number of Unixoid installations runs Debian or a derivate thereof, where `/bin/sh` must fulfil a number of additional guarantees (e.g. `local` must be available (excluding AT&T ksh), `echo` behaviour is prescribed, `test` must have `-a` and `-o`, and some XSI extensions must be available).

Therefore, I’d suggest to change the affected text to…

> mrsh provides a binary suitable as `/bin/sh` on POSIX systems¹ and a library for building new shells.

… and add a footnote that `this does not apply to Debian and derivatives thereof, such as Ubuntu, Linux Mint and KDE neon`.

Search the website for the sentence stating that mrsh provides a binary suitable as `/bin/sh`, then inspect the surrounding documentation. Update the wording to include the POSIX-systems qualification and add the requested Debian-derivatives footnote; done means the website clearly includes both changes.

Written by the indexing model from the issue text.