Add link to WP Academy on WikiPathways page

Add a link to https://academy.wikipathways.org/stages/sig-start/ on https://pfocr.wikipathways.org/browse/wikipathways.html. For example, add the following sentence after the current intro sentence:

"A tutorial with detailed instructions is available on <a href="https://academy.wikipathways.org/stages/sig-start/" target="_blank">WikiPathways Academy</a>."