Auto merge of #3451 - zancas:master, r=daira

Revise help output for z_sendmany

The previous version of the usage message for z_sendmany used the word "Change"
in an ambiguous way.

The intent was to describe "Change" the noun that indicates the portion of a
transaction's funds that are returned to the payer, however the context did not
provide an immediate cue to differentiate from the verb form meaning
"to alter".  Indeed, in other help strings in the same file that meaning of the
word is correct, i.e. the verb form is used.  Moreover a typo in the form of a
missing "a" later in the same sentence exacerbated the problem, by decreasing
readability precisely where context could reduce confusion.

diff --cc src/wallet/rpcwallet.cpp
Simple merge