Added first draft of notes from week 7
Changed exercise to theorem for the characterization of paths in Sigma types
added transport properties of identity types
added Homotopy Types section

- added Homotopy Types section
- changed title of section 3
updated week7 notes
Revert e1f4823..4745de1

This rolls back to commit e1f4823084bae5579cc2b5678d6bdc3bc2cc8a8d.
Updated week7 notes
Revert 4745de1..3964a2a

This rolls back to commit 4745de1b8b5bf362eca22215cd921fb9c9a6909d.
updated some sections of week7 notes