docs: grammar fixes to qmp-events

docs: grammar fixes to qmp-events

When converting to qmp events, commits 7cfadb6b and a6330785
fixed some grammar as part of moving text between files.  But
since dfab4892 later restored this file to the state prior to
qmp events, we have to do it again.

* docs/qmp/qmp-events.txt (RESET, SPICE_INITIALIZED): Tweak.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Wenchao Xia <wenchaoqemu@gmail.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>