message: Amend supported compiler docs
  This simplifies the text of the "older than tested" paragraph so
  readers don't miss the main point.  It also adds a link to JIRA
  for bug reports.
diff: @@ -24,12 +24,12 @@ We currently test the driver with the following configurations:
  VS | n/a | n/a | 14 (2015) Update 3
  boost | - | 1.5.3 | 1.6.0
  -With the exception of Visual Studio (for which mongocxx supports version 14
  -update 1 and newer), versions older the the ones listed may not work and are not
  +Versions older the the ones listed may not work and are not
  supported; use them at your own risk.
  Versions newer than the ones listed above should work; if you
  -have problems, please file a bug report or JIRA ticket.
  +have problems, please file a bug report via
  +[JIRA](https://jira.mongodb.org/browse/CXX/).
  ## Installation
  