README.md: added comma

Author: xternet

README.md

@@ -31,7 +31,7 @@ network where nobody has special authority over the execution, and thus they all
 ownership, voting, and other kinds of logic.
 
 When deploying contracts, you should use the latest released version of
-Solidity. This is because breaking changes, as well as new features and bug fixes are
+Solidity. This is because breaking changes, as well as new features and bug fixes, are
 introduced regularly. We currently use a 0.x version
 number [to indicate this fast pace of change](https://semver.org/#spec-item-4).