Add Account framework docs and guides (#5660)

contracts/utils/cryptography/signers/MultiSignerERC7913.sol

@@ -160,7 +160,8 @@ abstract contract MultiSignerERC7913 is AbstractSigner {
      *
      * Requirements:
      *
-     * * The {signers}'s length must be `>=` to the {threshold}. Throws {MultiSignerERC7913UnreachableThreshold} if not.
+     * * The {getSignerCount} must be greater or equal than to the {threshold}. Throws
+     * {MultiSignerERC7913UnreachableThreshold} if not.
      */
     function _validateReachableThreshold() internal view virtual {
         uint256 signersLength = _signers.length();

contracts/utils/cryptography/signers/SignerERC7913.sol

@@ -21,6 +21,10 @@ import {SignatureChecker} from "../SignatureChecker.sol";
  *     function initialize(bytes memory signer_) public initializer {
  *       _setSigner(signer_);
  *     }
+ *
+ *     function setSigner(bytes memory signer_) public onlyEntryPointOrSelf {
+ *       _setSigner(signer_);
+ *     }
  * }
  * ```
  *