Actually I think that extra backslash is correct, that is the example in user.config, but you don't really have to specify the path if keeping it under the default location /Data/sqlitedb you can just put
<add key="SqliteConnectionString" value="defaultdblocation" />
what he posted with a path is in comments and not used, or if it is not in comments and is exactly like this:
<add key="SqliteConnectionString" value="version=3,URI=file:C:\\Websites\Domain Name\Data\sqlitedb\mojoportal.db" />
<add key="SqliteConnectionString" value="defaultdblocation" />
the bottom one wins
Best,
Joe