Fix a grammaro.

llvm-svn: 100877
diff --git a/llvm/docs/CodeGenerator.html b/llvm/docs/CodeGenerator.html
index 1159a6c..fbdc294 100644
--- a/llvm/docs/CodeGenerator.html
+++ b/llvm/docs/CodeGenerator.html
@@ -1430,7 +1430,7 @@
    instruction,
    use <tt>TargetInstrInfo::get(opcode)::ImplicitUses</tt>. Pre-colored
    registers impose constraints on any register allocation algorithm. The
-   register allocator must make sure that none of them is been overwritten by
+   register allocator must make sure that none of them are overwritten by
    the values of virtual registers while still alive.</p>
 
 </div>