mk: Talk about `make clean` in the build help

diff --git a/Makefile.in b/Makefile.in
index fb8b1ce9371c98a2ca22a0f0ad0f09bc286ca42e..04ff606d0b93991c71f87a8870bffa372fcc2dfb 100644 (file)
--- a/Makefile.in
+++ b/Makefile.in
@@ -19,13 +19,17 @@
 #
 # First, start with one of these build targets:
 #
-#   * all - The default. Builds a complete, bootstrapped compiler.
+#   * all - The default. Build a complete, bootstrapped compiler.
 #           `rustc` will be in `${target-triple}/stage2/bin/`. Run it
 #           directly from the build directory if you like. This also
 #           comes with docs in `doc/`.
 #
 #   * check - Run the complete test suite
 #
+#   * clean - Clean the build repertory. It is advised to run this
+#             command if you want to build Rust again, after an update
+#             of the git repository.
+#
 #   * install - Install Rust. Note that installation is not necessary
 #               to use the compiler.
 #
@@ -152,7 +156,7 @@
 # libraries are managed and versioned without polluting the common
 # areas of the filesystem.
 #
-# General rust binaries may stil live in the host bin directory; they
+# General rust binaries may still live in the host bin directory; they
 # will just link against the libraries in the target lib directory.
 #
 # Admittedly this is a little convoluted.