Add documentation for DSL methods

[DanielRamosAcosta]

By now this PR adds documentation for the addDependency addPrimary and addDerived functions.

@hannahhoward I want to document the define, initializeWith and build... but the documentation I've added is well so far?

[coveralls]

Pull Request Test Coverage Report for Build 43

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 97.826%

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Totals
Change from base Build 42:	0.0%
Covered Lines:	133
Relevant Lines:	134

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💛 - Coveralls

[hannahhoward]

Thank you! This looks great! Merging.