* Doc: fix broken formatting in markdown #headers
Insert a space in markdown headers between the #'s and the header text.
(It appears that the space is required since a github update a year ago
https://github.com/blog/2100-github-pages-now-faster-and-simpler-with-jekyll-3-0)
* Update REST-interface.md
* Update guide-startmany.md
* Update instantsend.md
* Update keepass.md
* Update release-process.md
