fix typo (#64)

Author: nann-cheng

INSTALLATION.md

@@ -287,7 +287,7 @@ mpcium start -n node2
 
 ---
 
-## Apendix
+## Appendix
 
 ### Decrypt initiator private key with age
 

SECURITY.md

@@ -5,7 +5,7 @@
 Mpcium implements a threshold signature scheme with industry-standard security practices to protect cryptographic operations:
 
 1. **Distributed Trust**: No single entity possesses complete private keys
-2. **Threshold Cryptography**: Requires t+1 nodes to participate in signing operations
+2. **Threshold Cryptography**: Requires t-out-of-n nodes to participate in signing operations
 3. **End-to-End Verification**: All communications are signed and verified
 4. **Defense in Depth**: Multiple layers of encryption and verification