docs: add credential priority documentation and fix brew tap command

- Add credential hierarchy section to troubleshooting
- Add credential priority to profile setup docs
- Fix brew tap command to joshrotenberg/brew
- Set mdbook fold level to 0 (closed by default)
- Update DEMO.md profile commands to use --deployment flag

Author: joshrotenberg

docs/src/reference/troubleshooting.md

@@ -58,20 +58,57 @@ brew install ca-certificates
 
 ## Authentication Issues
 
+### Credential Priority Hierarchy
+
+**IMPORTANT:** redisctl uses credentials in this priority order (highest to lowest):
+
+1. **Environment Variables** (highest priority)
+2. **Profile Configuration**
+3. **CLI Flags** (lowest priority)
+
+This means environment variables will **override** your profile settings!
+
+**Common Issue:** Profile credentials not being used
+
+**Diagnosis:**
+```bash
+# Check for environment variables
+env | grep REDIS
+
+# Run with verbose logging to see which credentials are used
+redisctl -vv cloud subscription list 2>&1 | grep -i "using.*credentials"
+```
+
+**Solution:**
+```bash
+# Unset environment variables to use profile
+unset REDIS_CLOUD_API_KEY
+unset REDIS_CLOUD_SECRET_KEY
+unset REDIS_CLOUD_API_URL
+
+# For Enterprise
+unset REDIS_ENTERPRISE_URL
+unset REDIS_ENTERPRISE_USER
+unset REDIS_ENTERPRISE_PASSWORD
+
+# Verify profile is now used
+redisctl -vv cloud subscription list
+```
+
 ### Invalid Credentials
 
 **Problem:** `401 Unauthorized` or `Authentication failed`
 
 **Diagnosis:**
 ```bash
-# Test credentials directly
-redisctl auth test --profile prod
-
-# Check environment variables
+# Check environment variables first
 env | grep REDIS
 
 # Verify profile configuration
 redisctl profile show prod
+
+# Use verbose logging to see which credentials are being used
+redisctl -vv cloud account get 2>&1 | head -20
 ```
 
 **Solutions:**

docs/src/walkthrough/03-setup.md

@@ -74,6 +74,16 @@ redisctl profile set prod --deployment cloud \
   --use-keyring
 ```
 
+## Credential Priority
+
+**IMPORTANT:** Credentials are used in this order (highest to lowest):
+
+1. **Environment Variables** ← Will override profiles!
+2. **Profile Configuration**
+3. **CLI Flags**
+
+If you have `REDIS_CLOUD_API_KEY` set in your environment, it will be used instead of your profile credentials. Use `unset REDIS_CLOUD_API_KEY` to use profile credentials.
+
 ## Docker Compose Demo
 
 Try the complete Enterprise demo: