small doc fixes

[coveralls]

Pull Request Test Coverage Report for Build 1343482010

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 89 unchanged lines in 12 files lost coverage.
• Overall coverage decreased (-2.3%) to 54.484%

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Files with Coverage Reduction	New Missed Lines	%
src/Branch.jl	1	66.67%
src/newick.jl	1	75.8%
src/TreeSet.jl	1	42.86%
src/Node.jl	2	42.11%
src/trim.jl	2	90.63%
src/Interface.jl	3	50.83%
src/rand.jl	3	59.09%
src/Tree.jl	3	80.0%
src/Iterators.jl	8	85.71%
src/LinkTree.jl	9	57.45%
<!--	Total:	89		-->

Totals
Change from base Build 1342105515:	-2.3%
Covered Lines:	1045
Relevant Lines:	1918

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💛 - Coveralls