[glib] (13 commits) ...Merge branch 'cleanup-root' into 'main'

[Philip Withnall <pwithnall src gnome org>]

Summary of changes:

  f371d71... docs: Drop AUTHORS file in favour of git log
  9817ae7... ci: Move clang-format-diff.py into CI directory
  403bcda... docs: Drop README file in favour of README.md
  cdb0cc8... docs: Move README.rationale to docs subdirectory
  3707c21... docs: Drop README.win32 in favour of README.win32.md
  b927085... docs: Move INSTALL.in to INSTALL.md
  8a30ce9... docs: Reformat INSTALL.md as Markdown
  8a3583a... docs: Merge NEWS.pre-1-3 into NEWS
  7a569f6... tools: Move check-abis.sh from top-level to tools directory
  0dc5368... tools: Move glib-gettextize.in to tools directory
  5129750... tools: Move glib.supp to tools directory
  f78e288... tests: Move .test.in template files to tests directory
  5efbd51... Merge branch 'cleanup-root' into 'main'