Lowercase "Really Cool Feature" & minor edits

Here's my changes:
- I thought it was probably wrong that everywhere "Really Cool Feature" was all capitalized.
- I also added a link to a definition of "Mirabile dictu".
- changed a word or two to make it more clear.
- Added a newline before the `Polymorphic functions` heading so that hopefully it will render properly.
Merge pull request #593 from justgage/patch-1

Lowercase "Really Cool Feature" & minor edits
Update teaching-ocaml.md

Added course at ISAE/Supaéro.
Merge pull request #595 from dchemouil/patch-1

Update teaching-ocaml.md - Added course at ISAE/Supaéro
updated profiling on os x

Shark is long gone. Instruments works but does not give any useful function names, so profiling on OS X is essentially broken.
removed shark references
Merge pull request #597 from nilsbecker/patch-1

updated profiling on os x
fix capitalization of OCaml

Introduced in ddd9841fbaa5df7b1bc87da47d023a9300b4a8e7.