Fix typo in the "Distributed tracing with Linkerd" page

[GTRekter]

It's treating the config as a string rather than as an object.

[cratelyn]

@GTRekter i believe you'll need to amend your commit and add a DCO (developer certificate of origin) described here.

you can run something like:

git amend --signoff --no-edit && git push --force-with-lease

from your branch to push a new, amended commit.

[travisbeckham]

I think this needs to be fixed in 2-edge also.

[travisbeckham]

Now that the 2.18 docs are merged, we'll need to fix this in the 2.18 section as well.

[cratelyn]

i've opened https://github.com/linkerd/website/pull/1961 to carry this over the finish line.