Fix typos (#2723)

contracts/token/ERC20/ERC20.sol

@@ -203,9 +203,9 @@ contract ERC20 is Context, IERC20, IERC20Metadata {
     }
 
     /**
-     * @dev Moves tokens `amount` from `sender` to `recipient`.
+     * @dev Moves `amount` of tokens from `sender` to `recipient`.
      *
-     * This is internal function is equivalent to {transfer}, and can be used to
+     * This internal function is equivalent to {transfer}, and can be used to
      * e.g. implement automatic token fees, slashing mechanisms, etc.
      *
      * Emits a {Transfer} event.

contracts/utils/Address.sol

@@ -60,7 +60,7 @@ library Address {
 
     /**
      * @dev Performs a Solidity function call using a low level `call`. A
-     * plain`call` is an unsafe replacement for a function call: use this
+     * plain `call` is an unsafe replacement for a function call: use this
      * function instead.
      *
      * If `target` reverts with a revert reason, it is bubbled up by this