Fix a really tiny typo
Closes
@@ -8,7 +8,7 @@ title: Repository Rules
announce them.
An [external repository](../external.md) is a rule that can be used only
-in the `WORKSPACE` file and enable non-hermetic operation at the loading phase
+in the `WORKSPACE` file and enables non-hermetic operation at the loading phase
of Bazel. Each external repository rule creates its own workspace, with its
own BUILD files and artifacts. They can be used to depend on third-party
libraries (such as Maven packaged libraries) but also to generate BUILD files
