You are getting this error because you don't have a title in intro.rst
.
In order to fix this, add a title to intro.rst
. Suppose you want your title to be My Title
, then the title can be added by making the following two lines the first lines of intro.rst
:
My Title
*********
Note that you must have enough *
characters to completely underline your title, else you will get another error about a malformed title or underlining thereof.