Merge from origin/emacs-28

1e4b04c Improve documentation of filling and justification commands
9fd396e * lisp/progmodes/subword.el (superword-mode): Doc fix.  (Bug#...
e303cb1 Fix indexing of module functions that return complex types.

diff --cc doc/lispref/internals.texi
Simple merge

diff --cc doc/lispref/text.texi
Simple merge

diff --cc lisp/textmodes/fill.el
Simple merge