Sourcegraph's GitHub discussions have been defunct for awhile, but links
to them persisted in READMEs and documentation.
## Test plan
Documentation update only.
I don't see many uses of log.WithTrace, but I think this is because it
is clunky to use since Span or Context may be nil on a context. This
introduces a helper so we can start logging against a span more easily.
Here is an example of using it I want:
logger := trace.Logger(ctx, s.Log).Scoped("...", "...").With(...
This seems like the best place to add the logger, since we need to use
internal functions in the trace pkg (ie won't work in lib/log).
I updated the documentation to include an example of it. Right now the
documentation has one other place it calls WithTrace, but it needs to be
reworked to be more realistic. I think calling log.Scoped on something
that is traced seems surprising to me.
Test Plan: unused, so just that CI is happy.
Co-authored-by: Robert Lin <robert@bobheadxi.dev>
