docs: Wrong error level in the "Code. Update. Repeat." chapter of the tutorial

[SergiyKolesnikov]

In the "Let’s test it out:" list, Point 3 states: "Find the logLevel line and change it from 'error' to 'info'". Although, in the source code the logLevle is set to 'warn'. So, Point 3 should read "Find the logLevel line and change it from 'warn' to 'info'".

[nicks]

thanks for the report!