docs/RELEASE-PROCEDURE.md: renamed to use .md extension

Closes #2663

docs/RELEASE-PROCEDURE

@@ -1,96 +0,0 @@
-curl release procedure - how to do a release
-============================================
-
-in the source code repo
------------------------
-
-- edit `RELEASE-NOTES` to be accurate
-
-- update `docs/THANKS`
-
-- make sure all relevant changes are committed on the master branch
-
-- tag the git repo in this style: `git tag -a curl-7_34_0`. -a annotates the
-  tag and we use underscores instead of dots in the version number. Make sure
-  the tag is GPG signed (using -s).
-
-- run "./maketgz 7.34.0" to build the release tarballs. It is important that
-  you run this on a machine with the correct set of autotools etc installed
-  as this is what then will be shipped and used by most users on *nix like
-  systems.
-
-- push the git commits and the new tag
-
-- gpg sign the 4 tarballs as maketgz suggests
-
-- upload the 8 resulting files to the primary download directory
-
-in the curl-www repo
---------------------
-
-- edit `Makefile` (version number and date),
-
-- edit `_newslog.html` (announce the new release) and
-
-- edit `_changes.html` (insert changes+bugfixes from RELEASE-NOTES)
-
-- commit all local changes
-
-- tag the repo with the same name as used for the source repo.
-
-- make sure all relevant changes are committed and pushed on the master branch
-
-  (the web site then updates its contents automatically)
-
-on github
----------
-
-- edit the newly made release tag so that it is listed as the latest release
-
-inform
-------
-
-- send an email to curl-users, curl-announce and curl-library. Insert the
-  RELEASE-NOTES into the mail.
-
-celebrate
----------
-
-- suitable beverage intake is encouraged for the festivities
-
-curl release scheduling
-=======================
-
-Basics
-------
-
-We do releases every 8 weeks on Wednesdays. If critical problems arise, we can
-insert releases outside of the schedule or we can move the release date - but
-this is very rare.
-
-Each 8 week release cycle is split in two 4-week periods.
-
-- During the first 4 weeks after a release, we allow new features and changes
-  to curl and libcurl. If we accept any such changes, we bump the minor number
-  used for the next release.
-
-- During the second 4-week period we do not merge any features or changes, we
-  then only focus on fixing bugs and polishing things to make a solid coming
-  release.
-
-Coming dates
-------------
-
-Based on the description above, here are some planned release dates (at the
-time of this writing):
-
-- July 11, 2018
-- September 5, 2018
-- October 31, 2018
-- December 26, 2018
-- February 20, 2019
-- April 17, 2019
-- June 12, 2019
-- August 7, 2019
-- October 2, 2019
-- December 27, 2019