Fix documentation on convertValue()

[Logic-32]

#2220 changed ObjectMapper.convertValue() to always (de)serialize values instead of trying to intelligently return an object if it doesn't need converted but the documentation still suggest it is trying to be intelligent. Can the docs be updated to reflect current behavior?

Ref:

jackson-databind/src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java

Line 2072 in 0d17325

* If given value is already of requested type, value is returned as is.

[cowtowncoder]

Good point, yes.

[cowtowncoder]

Updated javadocs for ObjectMapper in 2.10.