Revert "doc: update for renaming --query_expansion to --query_expander"

This reverts commit 4837201f9fd01826c4dd21ced2b3f357a9e9bfcd.

I forgot to add renamed files. Sorry...
doc: update for renaming --query_expansion to --query_expander

TODO: .po should be updated in release process for this month. :p

(Renamed files are also included!)