Doc: Add section about restoreNoteRevision command to FAQ for note re…

…storation (laurent22#5638)

* docs: add section about restoreNoteRevision command to restore accidentally deleted notes

* docs:add link to wiki post

readme/faq.md

@@ -65,6 +65,13 @@ When changing the WebDAV URL, make sure that the new location has the same exact
 6. Synchronise to verify that everything is working.
 7. Do step 5 and 6 for all the other Joplin clients you need to sync.
 
+## I deleted some notes by accident and don't have a backup
+
+If you know the `NOTE_ID` and have note history enabled you can run the command `restoreNoteRevision` from the command palette e.g. `restoreNoteRevision 66457326a6ba4adeb4be8ce05e37af0d`. Joplin will then confirm if the restore was successful and place the note in a "Restored Note" notebook.
+If you do not know the `NOTE_ID` then you can find this within the Joplin sqlite database as the `item_id` within the `deleted_items` or `revisions` tables. It will require some manual checking of the `title_diff` and `body_diff` fields to check if the `ITEM/NOTE_ID` you are targeting is the correct one.
+You should first take a copy of the database to avoid making any accidental changes in the live one.
+For further information go [here](https://discourse.joplinapp.org/t/restoring-deleted-notes/21304).
+
 ## How can I easily enter Markdown tags in Android?
 
 You may use a special keyboard such as [Multiling O Keyboard](https://play.google.com/store/apps/details?id=kl.ime.oh&hl=en), which has shortcuts to create Markdown tags. [More information in this post](https://discourse.joplinapp.org/t/android-create-new-list-item-with-enter/585/2?u=laurent).