Fix word casing in the README

Changed `Actual` to `actual` mid sentence

README.md

@@ -85,7 +85,7 @@ In the future, mruby might ask you to distribute your new code
 (that you will commit,) under the MIT License as a member of
 "mruby developers" but contributors will keep their copyright.
 (We did not intend for contributors to transfer or waive their copyrights,
-Actual copyright holder name (contributors) will be listed in the [AUTHORS](AUTHORS)
+actual copyright holder name (contributors) will be listed in the [AUTHORS](AUTHORS)
 file.)
 
 Please ask us if you want to distribute your code under another license.