sql: add FLUSH PRIVILEGES hint (#835)
sql: add FLUSH PRIVILEGES hint (#835)

* Add FLUSH PRIVILEGES hint to user-account-management.md and FAQ.md

See https://github.com/photoprism/photoprism/issues/60#issuecomment-448971521

* FLUSH PRIVILEGES only required if grant table was modified

* Fix wording: grant tables

* Change wording as requested

* Change link as requested

* Use backticks to format title as code

Co-Authored-By: lastzero <17b9e1c64588c7fa6419b4d29dc1f4426279ba01@lastzero.net>

pingcap/docs,pingcap/docs,pingcap/docs