Clarify when actions are run

[dmcassel]

When running match functions like findDocumentMatchesByOptionsName, the results indicate what documents matched, what threshold those matches hit, and what action should be taken with them. It does not run those actions, but provides enough information that the caller can run them. When calling processMatchAndMerge, the actions are run automatically.
Clarify the documentation to make it clear that the match functions are a read-only activity.

[damonfeldman]

Would be nice to point out that there is (I hope) also a read-only merge function that returns the merged record for review or other use, without updating the DB.

[dmcassel]

There is (call merging:build-merge-models-by-uri instead of merging:save-merge-models-by-uri or pass rs:preview=true to the sm-merge REST extension). Makes sense to point that out as well.