Update token docs

[critesjosh]

this PR: AztecProtocol/aztec-packages#9606

From Jan:
I recently did a ton of changes to the token:

• introduced new "shield" flow that leverages partial notes,
• nuked the old "shield" flow,
• renamed a few functions (that should already be fixed in the docs),
• updated token bridging to use the new "shield" flow.

Since the token is used quite widely a lot of the docs is quite outdated.
Anything that contains the following words needs to get updated:secret_hash_for_redeeming_minted_notes, shield, redeem_shield or TransparentNote . The secret_hash_for_redeeming_minted_notes should not be in the docs anywhere because now the L1->L2 message never contains that value since there is no longer any TransparentNote (that hash was the hash used in the transparent note).