do not invent a name

Nowhere else is this called "Dist check"

Author: tshepang

src/doc/rustc-dev-guide/src/tests/intro.md

@@ -111,7 +111,7 @@ and it can be invoked so:
 
 This requires building all of the documentation, which might take a while.
 
-### Dist check
+### `distcheck`
 
 `distcheck` verifies that the source distribution tarball created by the build
 system will unpack, build, and run all tests.