removed dead link to stack.sh.html

the referenced file was removed with the following change
Ie7f4b265368f1d10a8908d75e11d625b2cc39e7c

Change-Id: I0e25b1f38e0969037d1c8af367432da56bb12e92

Author: Bernd Mueller

doc/source/index.rst

@@ -63,15 +63,12 @@ Quick Start
 
        devstack/tools/create-stack-user.sh; su stack
 
-#. Start the install
+#. Start the install, this will take a few minutes.
 
    ::
 
        cd devstack; ./stack.sh
 
-   It takes a few minutes, we recommend `reading the
-   script <stack.sh.html>`__ while it is building.
-
 Guides
 ======