[SQLite] Add help text in sqlitedb template

[tmdoit-zz]

About path to the database file.

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Proposed changes

Checklist

• I have read the contribution guidelines
• For non-bugfix PRs, I have discussed this change on the mailing list/slack team.
• I have run grunt to verify the unit tests pass
• I have added suitable unit tests to cover the new/changed functionality

[coveralls]

Coverage remained the same at 66.256% when pulling 243818a on tmdoit:patch-1 into 5f22603 on node-red:master.

[coveralls]

Coverage remained the same at 66.256% when pulling 243818a on tmdoit:patch-1 into 5f22603 on node-red:master.