tex-everysel{,-doc}: add version 2.1

The package provided hooks whose arguments are executed just
after LaTeX has loaded a new font by means of \selectfont. It
has become obsolete with LaTeX versions 2021/01/05 or newer,
since LaTeX now provides its own hooks to fulfill this task.
For newer versions of LaTeX everysel only provides macros using
LaTeX's hook management due to compatibility reasons. See
lthooks-doc.pdf for instructions how to use lthooks instead of
everysel.

(markd)