Fix NatSpec and documentation errors

[dsoko1ov]

Fixes incorrect NatSpec parameter names and typos in documentation.

UnbuttonWrapping.sol:

• @param sender → @param recipient for the third parameter (lines 35, 56) - the actual function
  signature uses recipient, not sender
• underling → underlying (line 36)

README.md:

• must be take → must be taken (grammar fix)

No functional changes.