improved instrumentation.subscribe docs
[DOC beta] Fix typo in name for `customEvents`

As noticed by @alexdiliberto in http://git.io/KD6Lzg
[DOC beta] Update enumerable.js
[DOC beta] adds more docs to transitionTo
Fix documentation error

Was `Context` and should be `Contact`
Programmatic has two "m"s
[DOC] Clarifies typical sendAction use

The previous docs focused heavily on the default behavior of sendAction
instead of the more typical use through configuration and this led
to some feedback about confusion, especially how it overlapped with
plain {{action}} use in the components own template.
Merge pull request #3778 from lukemelia/programatic

Programmatic has two "m"s
Merge pull request #3763 from southpolesteve/patch-1

Fix Ember.Freezable documentation error
Merge pull request #3761 from twokul/transitionTo-docs

[DOC beta] Adds more docs to transitionTo
Merge pull request #3759 from pangratz/fix/typos

[DOC beta] Fix typo in name for `customEvents`
Merge pull request #3757 from Dave-Choi/patch-1

Update enumerable.js
Merge pull request #3750 from billybonks/master

[DOC beta] instrumentation.subscribe
Merge pull request #3747 from trek/clarify-typical-send-action-use

[DOC] Clarifies typical sendAction use