Update README.md

Use --update-deps
Revert "Update README.md"

This reverts commit e31765a9f72b38a84b448f0b68ff7d6fc6bb3ed8.
add update-implies to info.rkt
add in- iterators
add make-default-tag-function
change project-require.rkt to directory-require.rkt
change project-require to directory-require (pt 2)
add txexpr validation to pollen/markup compile in DrRacket
change project-require to directory-require (pt 3)
updates to docs (including third tutorial)