Https://github.com/typescript-eslint/tslint-to-eslint-config/issues/856

Problem: Some terms were used ambiguously throughout the docs, e.g.
"underlying asset" could refer to Pendle market's asset or an SY token
or a yield token.

Solution:
* Use the term "underlying token" to refer to the oracle's underlying
  token (it can be either the market's asset or the yield token).
* Use the term "yield token" to refer to an interest-bearing token
  wrapped by SY.
* Use the term "market's asset" to refer to the underlying asset of
  the Pendle market. 1 PT will eventually be equivalent to 1 asset
  at redemption.