Clarify comments and test names in merkle tests
Clarify comments and test names in merkle tests

Renamed TestPaddedStorageProof to
TestNonMultipleNumberOfSegmentsStorageProof
and TestPartialLastLeafReadSegments to
TestNonMultipleNumberOfSegmentsReadSegments

Also fixed styling of comments (capitalize first word if it's not a type
and use punctuation to end a comment).

johnathanhowell/Sia,mnsl/Sia,NebulousLabs/Sia,Mingling94/Sia,mtlynch/Sia,mharkus/Sia,MrStrong/Sia,mtlynch/Sia,ChrisSchinnerl/Sia,ericflo/Sia,NebulousLabs/Sia,rivine/rivine,ericflo/Sia,mnsl/Sia,rivine/rivine,ChrisSchinnerl/Sia,MrStrong/Sia,mharkus/Sia