Proposal for token-swap curve using stake pool account (#1504)

* feat: add new curve proposal

* Update StakePoolStableCurve.md

Author: bartosz-lipinski

token-swap/proposals/StakePoolStableCurve.md

@@ -0,0 +1,9 @@
+# Combine Stable Curve with Stake Pool for price discovery
+
+Implement a curve for token-swap that accepts stake pool account and uses stable curve to swap assets. 
+[Stake pool account](https://github.com/solana-labs/solana-program-library/blob/master/stake-pool/program/src/state.rs#L17) will be used for initial price discovery then stable curve would be used to derive price based on the size of the order and available reserves.
+
+## Links
+1. Stake pool implementation: https://github.com/solana-labs/solana-program-library/blob/master/stake-pool/program
+2. AMM implementation: https://github.com/solana-labs/solana-program-library/blob/master/token-swap/program
+3. Stable curve: https://github.com/solana-labs/solana-program-library/blob/master/token-swap/program/src/curve/stable.rs