Assertions that req >1 evidence items must have evidence items from independent sources.

[lsheta]

Clarify in assertion docs that assertions which require >1 evidence items (i.e. Tier IIB) must come from at least two independent studies (not two different papers describing the same data).

We will want to beef up the AMP tier guidelines in the docs, as well. See this CGC presentation

[kkrysiak]

Ideally, this would also cover when a single paper is broken into more than one evidence item. We would want independent papers.