Fix grammar in source.rst

Author: vapniks

doc/readthedocs/debugger/commands/support/source.rst

@@ -8,7 +8,7 @@ Read and Run Debugger Commands from a File (`source`)
 
 Read debugger commands from the glob expansion of *file-glob*;
 
-*file-glob* should resolve after glob expansion to single file.
+*file-glob* should resolve to a single file after glob expansion.
 
 Examples:
 +++++++++