Add tip that welcome page will not show if using Rails 4.0.x.

Some students using Rails 4.0.x were confused about why the Welcome page showed on their localhost, but not when they pushed to Heroku.
Add a note to teaching tips to be well rested the day of teaching. [ci skip]
Reword tip that I just added about the default welcome page not showing on Heroku if using Rails 4.
removed superfluous 'feel'
Merge branch 'master' of https://github.com/SamSamskies/docs into SamSamskies-master
Merge pull request #225 from Alamoz/alamoz

Add a note to teaching tips to be well rested the day of teaching.
Merge pull request #228 from imurchie/master

removed superfluous 'feel'
fixed typo. [ci-skip]
Merge pull request #229 from tracyleeweiss/typo

fixed typo. [ci-skip]