Fix frontmatter descriptions, duplicate YAML blocks, title headings across 60 files

skills/implementing-aes-encryption-for-data-at-rest/SKILL.md

@@ -14,6 +14,21 @@ license: Apache-2.0
 
 AES (Advanced Encryption Standard) is a symmetric block cipher standardized by NIST (FIPS 197) used to protect classified and sensitive data. This skill covers implementing AES-256 encryption in GCM mode for encrypting files and data stores at rest, including proper key derivation, IV/nonce management, and authenticated encryption.
 
+
+## When to Use
+
+- When deploying or configuring implementing aes encryption for data at rest capabilities in your environment
+- When establishing security controls aligned to compliance requirements
+- When building or improving security architecture for this domain
+- When conducting security assessments that require this implementation
+
+## Prerequisites
+
+- Familiarity with cryptography concepts and tools
+- Access to a test or lab environment for safe execution
+- Python 3.8+ with required dependencies installed
+- Appropriate authorization for any testing activities
+
 ## Objectives
 
 - Implement AES-256-GCM encryption and decryption for files