* README.md: fix slight grammatical error by @abwinkler999.

[fix GH-659]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46799 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

README.md

@@ -87,7 +87,7 @@ This is what you need to do to compile and install Ruby:
     module names if not present), if you want to link modules statically.
 
     If you don't want to compile non static extension modules (probably on
-    architectures which does not allow dynamic loading), remove comment mark
+    architectures which do not allow dynamic loading), remove comment mark
     from the line "`#option nodynamic`" in `ext/Setup`.
 
     Usually this step will not be needed.