[doc][xs]: fix typo in install command (thx Aron!).
[doc][xs]: fix typo in install command (thx Aron!).

nobita-isc/annotator-store,nobita-isc/annotator-store,openannotation/annotator-store,nobita-isc/annotator-store,nobita-isc/annotator-store,ningyifan/annotator-store,happybelly/annotator-store