Document Export method

[cherry-john]

    > This can be done with `mysqldump`, and using the mysql delete command to remove other instances. Access tokens etc can then be deleted by truncating those tables, but this is a quick manual process.

Based on the schema, my take is that when migrating from one server to anohter, delete all instances except the one you want to migrate.

Next, delete all users where userInstances = null for their userid

Then, remove any assetsBarcodes without an instanceId set

Truncate:

• auditLog
• authTokens
• emailSent
• emailVerificationCodes
• loginAttempts
• passwordResetCodes

@cherry-john could you add the above to #21 next time you're looking at it?

Originally posted by @Jbithell in adam-rms/adam-rms#178 (comment)