> Shell scripts and lists of implementations belong in the repo, because they
> change over time.
The "srfi-nnn.html" file is in the repo, so it can change as easily as
the sample implementation.
The only changes that may be made to a final SRFI are:
1) updating of URLs (including those of related SRFIs)
2) noting that the SRFI has been deprecated or has been superseded by a subsequent SRFI [this is now done on the home page]
3) withdrawing the SRFI, but only with permission of the author, and only if a replacement SRFI has been made final [this also is done on the home page]
4) improving the sample implementation and tests [not really a change to the SRFI as such]
5) correcting errors (but not errors of design), e.g. spelling errors, typos, or contradictory statements
We have stretched this a bit by adding "post-finalization notes" to the Status section of a few SRFIs, containing recommendations on parts of the SRFI that the author thinks implementers should not implement or should implement differently. SRFI 113 is an extreme example with two such notes. If we ever have a SRFI for immutable sets, SRFI 113 may add a third saying that implementers should support mutable sets, although the SRFI gives them the choice of mutable or immutable.
As you can see, adding a new supported implementation isn't covered by this list.