zephyr-env.sh: fix stale comment

s/zephyr-env_install.bash/.zephyrrc/

Change-Id: I88d4a5d44b6fb97d52b8244cb3d1bcb8679b49ef
Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
diff --git a/zephyr-env.sh b/zephyr-env.sh
index d758a8d..39656c5 100644
--- a/zephyr-env.sh
+++ b/zephyr-env.sh
@@ -32,7 +32,7 @@
 fi
 
 # You can further customize your environment by creating a bash script called
-# zephyr-env_install.bash in your home directory. It will be automatically
+# .zephyrrc in your home directory. It will be automatically
 # run (if it exists) by this script.
 
 uname | grep -q -P "MINGW|MSYS" && PWD_OPT="-W"