Add description of “gnt-instance startup --force” to manpage.
Add description of “gnt-instance startup --force” to manpage.

This was reported by Henning Sprang in issue #14. Also add a missing word
in the description of “gnt-instance reboot”.

Reviewed-by: iustinp


mbakke/ganeti,bitemyapp/ganeti,grnet/snf-ganeti,onponomarev/ganeti,apyrgio/snf-ganeti,yiannist/ganeti,ganeti/ganeti,mbakke/ganeti,mbakke/ganeti,onponomarev/ganeti,apyrgio/snf-ganeti,grnet/snf-ganeti,andir/ganeti,yiannist/ganeti,leshchevds/ganeti,apyrgio/ganeti,ganeti/ganeti,yiannist/ganeti,dimara/ganeti,leshchevds/ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,ganeti/ganeti,andir/ganeti,leshchevds/ganeti,bitemyapp/ganeti,apyrgio/ganeti,ganeti-github-testing/ganeti-test-1,dimara/ganeti