fix(snippets): add UNNUMBERED notoc to sub-headings in adr/meeting/weekly

Sub-headings (Problem statement, Decision, etc.) should not appear in
TOC when using #+OPTIONS: toc:N. Main template heading remains in TOC.

snippets/org-mode/meeting

@@ -9,8 +9,17 @@
 | *Attendees* | ${2:names}                        |
 
 `(make-string (+ 2 (or (org-current-level) 0)) ?*)` Notes
+:PROPERTIES:
+:UNNUMBERED: notoc
+:END:
 
 `(make-string (+ 2 (or (org-current-level) 0)) ?*)` Actions
+:PROPERTIES:
+:UNNUMBERED: notoc
+:END:
 
 `(make-string (+ 2 (or (org-current-level) 0)) ?*)` Next steps
+:PROPERTIES:
+:UNNUMBERED: notoc
+:END:
 $0