Fix typos

contracts/bsc-tendermint/lib/RLPDecode.sol

@@ -131,7 +131,7 @@ library RLPDecode {
         assembly {
             result := mload(memPtr)
 
-            // shfit to the correct location if neccesary
+            // shfit to the correct location if necessary
             if lt(len, 32) {
                 result := div(result, exp(256, sub(32, len)))
             }

contracts/bsc-tendermint/lib/proto/ProtoBufRuntime.sol

@@ -1785,7 +1785,7 @@ library ProtoBufRuntime {
 
     /**
      * @dev Encode Solidity type
-     * @param x The unsinged integer to be encoded
+     * @param x The unsigned integer to be encoded
      * @param sz The number of bytes used to encode Solidity types
      * @param p The offset of bytes array `bs`
      * @param bs The bytes array to encode

contracts/message-bridge/libraries/RLPReader.sol

@@ -211,7 +211,7 @@ library RLPReader {
         assembly {
             result := mload(memPtr)
 
-            // shift to the correct location if neccesary
+            // shift to the correct location if necessary
             if lt(len, 32) {
                 result := div(result, exp(256, sub(32, len)))
             }

test/poa/PoAUnitTest.spec.ts

@@ -49,7 +49,7 @@ describe('PoAUnitTest', async () => {
     return poaUintTest;
   }
 
-  it('should pass retrive part of bytes', async () => {
+  it('should pass retrieve part of bytes', async () => {
     const testBytes = '0x7894745829abbdfe75814218613412afed1238907ba0';
     const bytesLength = testBytes.length / 2 - 1;