restructure site nav

mkdocs.yml

@@ -9,6 +9,7 @@ extra_css:
     - stylesheets/custom.css
 nav:
 - Home: index.md
+- Level 101:
     - Fundamentals Series:
         - Linux Basics:
             - Introduction: linux_basics/intro.md
@@ -76,6 +77,8 @@ nav:
         - Threat, Attacks & Defences: security/threats_attacks_defences.md
         - Writing Secure code: security/writing_secure_code.md
         - Conclusion: security/conclusion.md
+#- Level 102:
+ 
 - Contribute: CONTRIBUTING.md
 - Code of Conduct: CODE_OF_CONDUCT.md
 - SRE Community: sre_community.md