Add notes on how to deploy docs on Travis

doc/README.md

@@ -35,3 +35,18 @@ sudo tlmgr install ucs dvipng
 
 - Make sure to use pre-sphinxification paths to images
   (not the _images directory)
+
+
+## Auto-generating dev docs ##
+
+This set of instructions was used to create scikit-image/tools/deploy-docs.sh
+
+- Go to Github account settings -> personal access tokens
+- Create a new token with access rights `public_repo` and `user:email only`
+- Install the travis command line tool: `gem install travis`.  On OSX, you can get gem via `brew install ruby`.
+- Take then token generated by Github and run `travis encrypt GH_TOKEN=<token>` from inside a scikit-image repo
+- Paste the output into the secure: field of `.travis.yml`.
+- The decrypted GH_TOKEN env var will be available for travis scripts
+
+https://help.github.com/articles/creating-an-access-token-for-command-line-use/
+http://docs.travis-ci.com/user/encryption-keys/