Update README.md

Adjust wording about which versions are tested.

Author: MichaelHatherly

README.md

@@ -22,7 +22,7 @@ pkg> add DocStringExtensions
 
 ## Project Status
 
-The package is tested and developed against Julia `0.7` and `1.0` on Linux, OS X, and Windows,
+The package is tested and developed against Julia `1.0`, as well as the latest `stable` and `nightly` versions on Linux, OS X, and Windows,
 but there are versions of the package that works on older versions of Julia.
 
 ## Contributing and Questions