gnucash-docs: New Branch '3.1'

[John Ralls]

        at  https://github.com/Gnucash/gnucash-docs/tree/b552e1c80678f69db5f54e0717a53e2e084e3d23 (tag)
   tagging  09069e2a0b3c1aba265b57d20346f59426ee5e13 (commit)
  replaces  3.0
 tagged by  John Ralls
        on  Sun Apr 29 09:46:08 2018 -0700


Docs Release 3.1

John Ralls (4):
      Release Documentation for GnuCash 2.6.20
      Merge branch 'maint'
      Update supported platforms for version 3.x.
      Release Documentation for GnuCash 3.1.