docs: Only show 2nd level headings in TOC

.nvim.lua

@@ -0,0 +1,14 @@
+-- https://github.com/hedyhli/markdown-toc.nvim
+--
+-- outline.nvim README uses markdown-toc to auto-update the ToC.
+-- The following config makes only second level headings be included.
+
+local ok, mtoc = pcall(require, 'mtoc')
+if ok then
+  mtoc.update_config({
+    headings = {
+      pattern = '^(##)%s+(.+)$',
+    }
+  })
+end
+