Update mermaid version to 11.6.0

Uses very old version of mermaid.
Noticed that 11.6.0 version doesn't produce wide empty spaces below and under flowcharts/sequenceDiagrams, etc.

Author: mnbnkr

docs/_config.yml

@@ -23,7 +23,7 @@ author:
 
 # Mermaid settings
 mermaid:
-  version: "9.1.3"  # Pick the version you want
+  version: "11.6.0"  # Pick the version you want
   # Default configuration
   config: |
     directionLR
@@ -44,4 +44,4 @@ callouts:
 nav:
   - Home: index.md       # Link to your main docs index
   - GitHub: "https://github.com/The-Pocket/Tutorial-Codebase-Knowledge"
-  - Discord: "https://discord.gg/hUHHE9Sa6T"
+  - Discord: "https://discord.gg/hUHHE9Sa6T"