Update contract comments & reorganize for readability (#12)

* update PositionDetails and PositionBalance comments and fields

* consolidate public methods to the bottom of the contract

* remove comment references to restored functionality

* update contract comments

* update contract comments and reorganize for clarity

* update contract and construct internal methods

* update contract comments

* revert changes to PositionDetails balances field

* update contract comments

* Update cadence/contracts/TidalProtocol.cdc

Co-authored-by: Joshua Hannan <joshua.hannan@flowfoundation.org>

* update interest index & balance type comments

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Co-authored-by: Joshua Hannan <joshua.hannan@flowfoundation.org>

Author: sisyphusSmiling