add link to website/faq/cheatsheet

Summary: This diff adds a few useful links to our Readme.

Reviewed By: EdouardGrave

Differential Revision: D5807871

fbshipit-source-id: ca51c4b8b233327a07fc13e363da353c040e6216

README.md

@@ -1,6 +1,12 @@
 # fastText
 
-fastText is a library for efficient learning of word representations and sentence classification.
+[fastText](https://fasttext.cc/) is a library for efficient learning of word representations and sentence classification.
+
+## FAQ / Cheatsheet
+
+You can find [answers to frequently asked questions](https://fasttext.cc/docs/en/faqs.html#content) on our [website](https://fasttext.cc/).
+
+We also provide a [cheatsheet](https://fasttext.cc/docs/en/cheatsheet.html#content) full of useful one-liners.
 
 ## Requirements