docs: Improve JWT vulnerability section headings and code block formatting.

docs/Chapter_17_Plugin_and_API_Exploitation.md

@@ -1010,7 +1010,7 @@ JSON Web Tokens (JWT) are self-contained tokens that carry authentication and au
 
 A JWT consists of three parts separated by dots:
 
-```
+```text
 header.payload.signature
 ```
 
@@ -1146,14 +1146,14 @@ JWTs are stateless, but you can maintain a blacklist of revoked `jti` values (in
 - Account is compromised
 - Permissions change
 
-**Common JWT Vulnerabilities:**
+### Common JWT Vulnerabilities
 
-**1. Algorithm Confusion (alg=none)**
+#### 1. Algorithm Confusion (alg=none)
 
 - **Attack**: Change `alg` to `none`, remove signature
 - **Defense**: Always specify `algorithms` parameter in decode
 
-**2. Weak Secret Keys**
+#### 2. Weak Secret Keys
 
 ```python
 # ❌ Bad: Easily brute-forced
@@ -1163,7 +1163,7 @@ secret_key = "secret123"
 secret_key = secrets.token_urlsafe(64)
 ```
 
-**3. No Expiration**
+#### 3. No Expiration
 
 ```python
 # ❌ Bad: Token never expires
@@ -1173,7 +1173,7 @@ payload = {'user_id': 123}  # Missing 'exp'
 payload = {'user_id': 123, 'exp': time.time() + 3600}  # 1 hour
 ```
 
-**4. Storing Sensitive Data**
+#### 4. Storing Sensitive Data
 
 ```python
 # ❌ Bad: JWT payloads are Base64-encoded, NOT encrypted
@@ -1183,7 +1183,7 @@ payload = {'user_id': 123, 'password': 'secret123'}  # Visible to anyone!
 payload = {'user_id': 123, 'permissions': ['read']}
 ```
 
-**5. Not Validating Claims**
+#### 5. Not Validating Claims
 
 ```python
 # ❌ Bad: Accept any valid JWT