Add comments to Python ECDSA implementation
Add comments to Python ECDSA implementation

Github-Pull: #15826
Rebased-From: b67978529ad02fc2665f2362418dc53db2e25e17

myriadteam/myriadcoin,GroestlCoin/bitcoin,bespike/litecoin,GroestlCoin/GroestlCoin,myriadteam/myriadcoin,myriadcoin/myriadcoin,qtumproject/qtum,vertcoin/vertcoin,myriadcoin/myriadcoin,bespike/litecoin,myriadteam/myriadcoin,ahmedbodi/vertcoin,untrustbank/litecoin,GroestlCoin/GroestlCoin,GroestlCoin/bitcoin,untrustbank/litecoin,myriadteam/myriadcoin,bespike/litecoin,qtumproject/qtum,GroestlCoin/bitcoin,bespike/litecoin,GroestlCoin/bitcoin,myriadteam/myriadcoin,vertcoin/vertcoin,untrustbank/litecoin,vertcoin/vertcoin,bespike/litecoin,bespike/litecoin,GroestlCoin/GroestlCoin,GroestlCoin/GroestlCoin,ahmedbodi/vertcoin,qtumproject/qtum,vertcoin/vertcoin,vertcoin/vertcoin,untrustbank/litecoin,qtumproject/qtum,myriadcoin/myriadcoin,ahmedbodi/vertcoin,GroestlCoin/GroestlCoin,untrustbank/litecoin,myriadteam/myriadcoin,myriadcoin/myriadcoin,ahmedbodi/vertcoin,vertcoin/vertcoin,qtumproject/qtum,myriadcoin/myriadcoin,qtumproject/qtum,ahmedbodi/vertcoin,GroestlCoin/bitcoin,untrustbank/litecoin,qtumproject/qtum,GroestlCoin/bitcoin,myriadcoin/myriadcoin,ahmedbodi/vertcoin,GroestlCoin/GroestlCoin