Add lzchen to maintainers (#784)
Add lzchen to maintainers (#784)

* Add lzchen to maintainers

Closes #778.

Co-authored-by: alrex <1e5a92690ae5061b029620512ac8ae33d4f3a3b3@lightstep.com>
open-telemetry/opentelemetry-python,open-telemetry/opentelemetry-python