Updates readme with links to the User guide
Adds a "adding a mod" to contributions
Links to file testing instead of validator in bin
Merge remote-tracking branch 'Ippo343/master' into release-v1.0

* Ippo343/master:
  Links to file testing instead of validator in bin
  Adds a "adding a mod" to contributions
  Updates readme with links to the User guide
Merge branch 'release-v1.0'

* release-v1.0:
  Links to file testing instead of validator in bin
  Adds a "adding a mod" to contributions
  Updates readme with links to the User guide