Merge remote-tracking branch 'remotes/pmaydell/tags/pull-docs-20200306' into staging

docs:
 * Convert qemu-doc from Texinfo to rST

# gpg: Signature made Fri 06 Mar 2020 11:08:15 GMT
# gpg:                using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg:                issuer "[email protected]"
# gpg: Good signature from "Peter Maydell <[email protected]>" [ultimate]
# gpg:                 aka "Peter Maydell <[email protected]>" [ultimate]
# gpg:                 aka "Peter Maydell <[email protected]>" [ultimate]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-docs-20200306: (33 commits)
  *.hx: Remove all the STEXI/ETEXI blocks
  docs: Remove old texinfo sources
  docs: Stop building qemu-doc
  ui/cocoa.m: Update documentation file and pathname
  docs: Generate qemu.1 manpage with Sphinx
  docs: Split out sections for the manpage into .rst.inc files
  qemu-options.hx: Fix up the autogenerated rST
  qemu-options.hx: Add rST documentation fragments
  scripts/hxtool-conv: Archive script used in qemu-options.hx conversion
  docs: Roll -prom-env and -g target-specific info into qemu-options.hx
  docs: Roll semihosting option information into qemu-options.hx
  doc/scripts/hxtool.py: Strip trailing ':' from DEFHEADING/ARCHHEADING
  hmp-commands-info.hx: Add rST documentation fragments
  hmp-commands.hx: Add rST documentation fragments
  docs/system: convert Texinfo documentation to rST
  docs/system: convert the documentation of deprecated features to rST.
  docs/system: convert managed startup to rST.
  docs/system: Convert security.texi to rST format
  docs/system: Convert qemu-cpu-models.texi to rST
  docs: Create defs.rst.inc as a place to define substitutions
  ...

Signed-off-by: Peter Maydell <[email protected]>