Add docs on how to write to the OTOL API with curl
Properly create trees on Github and go don't indent our JSON for now

Tree paths should not start with a leading forward slash. The Github
API will allow you to create them successfully, but they create a corrupt
tree which prevents the repo from being clonable.

Deleting the branch containing the offending tree caused the repo to be
clonable again.

Previously we were indenting JSON 4 spaces, but all current JSON in treenexus
has indent=0. With this change, we get meaningful diffs of the changed JSON.
For example:

    https://github.com/OpenTreeOfLife/treenexus/compare/leto_study_9?expand=1