Update submission formatting guidelines

Updates the desired format for title, author, etc. in the
submission template, and tidies it up a little bit. Also
makes corrects and improvements to README to reflect these
Add short story The Call of Cthulhu by H. P. Lovecraft

I've added the key "title" under "publication" in the YAML front-
matter to refer to the publication/magazine in which the story was
originally published.
add submission guidelines and template
updates URL in README.md
initial commit