Include a second example

Add an example showing how to return the stream as the hint rather than a callback.   

Also demonstrate how gulp is smart about task dependency and doesn't rerun tasks that are mentioned multiple times.
return stream for styles task
fix typo and remove extra headers
fix typo in comment
+ brief descritions for ## Incremental Builds

All are similar, but not all the same.
only use js variants from interpret
Merge pull request #447 from tkellen/fasterpreload

only use js variants from interpret
Introduced link to a high quality intro video on tagtree.tv
Merge pull request #450 from hendrikswan/master

Introduced link to a high quality intro video on tagtree.tv
Merge pull request #441 from tomByrer/patch-1

+ brief descritions for ## Incremental Builds
fix wording and puncuation
update to use gulp-rimraf instead of gulp-clean
match require variable for rimraf
tweak some wording about completion hints
fix gulp --tasks output
Merge branch 'master' of https://github.com/gulpjs/gulp
Add missing punctuation.

To keep formatting consistent, each step title should end with a colon and all sentences should have ending punctuation.
Merge pull request #457 from edull24/patch-1

Add missing punctuation.
Remove duplicated test
Merge pull request #463 from hojs/duplicated-test

Remove duplicated test