Small grammar fix in rustdoc.md

Happened to be reading through

diff --git a/src/doc/rustdoc.md b/src/doc/rustdoc.md
index f5fbad960a3f5a0b0250de42ba50099af4332ea4..402687a812eeec5df2a824cc7602c62a9cb8927e 100644 (file)
--- a/src/doc/rustdoc.md
+++ b/src/doc/rustdoc.md
@@ -221,7 +221,7 @@ testing this code, the `fib` function will be included (so it can compile).
 
 Running tests often requires some special configuration to filter tests, find
 libraries, or try running ignored examples. The testing framework that rustdoc
-uses is build on crate `test`, which is also used when you compile crates with
+uses is built on crate `test`, which is also used when you compile crates with
 rustc's `--test` flag. Extra arguments can be passed to rustdoc's test harness
 with the `--test-args` flag.