update package descriptions

Closes #436

See merge request iris/iris!746

Prove missing fractional_big_sepL2

See merge request iris/iris!737

To match the suggestion in
iris/iris!737 (comment 75017).

fixes #437

Editor docs: add information on how to use vim for working with Iris

See merge request iris/iris!744

Normalize focused goal output

See merge request iris/iris!743

Merge the "1 focused goal" line with the subsequent "(shelved: 1)" line,
since this is the new output in Coq 8.15+.

Iris does not currently produce this output, since no test calls `Show`
with shelved goals, but this future-proofs the test normalization.

make f_contractive consistent with f_equiv

See merge request iris/iris!741

relax AsFractional Hint Mode

See merge request iris/iris!740

Optimize iDestruct by avoiding superfluous iRenames

See merge request iris/iris!733

Following up on the previous commit, this slightly generalizes the
lemmas associated to the intuitionistic/spatial/modalelim cases of
iDestruct to support renaming on the fly, and use these to save a
later renaming.

The idea is to avoid unnecessary calls to iRename: when choosing names
for sub-patterns, instead of generating fresh names or reusing an
existing (unrelated) name, if the sub-pattern is an identifier, then
directly chose this identifier as the new name, thus saving a rename
later on.

[triviality] Clarify funny proof of `tac_twp_cmpxchg_fail`

See merge request iris/iris!738

To avoid confusion from
iris/iris@d2c226e7 (comment 73999).

add big_sepL_take_drop

See merge request iris/iris!734

add big_sep*_sep_2 lemmas for merging bigops via iDestruct

See merge request iris/iris!736

Optimize iIntoEmpValid

See merge request iris/iris!729

With large proof contexts and lemmas with many forall quantifiers,
iIntoEmpValid can become quite slow. This makes it go faster by adding
"fast paths" for the -> and forall cases, gated by Ltac pattern
matching (which is faster than trying to unify with refine and fail).