This commit adds some documentation about build telemetry
to the build system documentation. This doc should be used
as a reference during opt-in to build system telemetry,
and includes paths to the relevant files for users to audit
independently. Documentation regarding the schema types and
object properties was generated by the `jsonschema2rst` tool,
available on PyPI.
Differential Revision: https://phabricator.services.mozilla.com/D8030
--HG--
extra : moz-landing-system : lando
Connor Sheehan