Update chunk types wtf-trace.md 
Update chunk types wtf-trace.md 

The type ID was inconsistent with the ID used in the code: https://github.com/google/tracing-framework/blob/master/src/wtf/io/cff/chunktype.js#L56
google/tracing-framework,google/tracing-framework,google/tracing-framework,google/tracing-framework