Don't forget to change into the correct directory

... if you are reading this not in the repo, but from the web page, you might
not know where to go to make all those nice commands work.

morph/grid/local/README.rst

@@ -9,6 +9,10 @@ Issues with networking that looked like guest misconfigurations vanished after c
 Use the local development environment
 `````````````````````````````````````
 
+0. Enter the morph local grid directory::
+
+    cd morph/grid/local
+
 1. Enter the project's nix-shell::
 
     nix-shell ../../../shell.nix