chore: Move editor into codebase (#2930)

shared/editor/rules/notices.ts

@@ -0,0 +1,21 @@
+import MarkdownIt from "markdown-it";
+import customFence from "markdown-it-container";
+import Token from "markdown-it/lib/token";
+
+export default function notice(md: MarkdownIt): void {
+  return customFence(md, "notice", {
+    marker: ":",
+    validate: () => true,
+    render: function (tokens: Token[], idx: number) {
+      const { info } = tokens[idx];
+
+      if (tokens[idx].nesting === 1) {
+        // opening tag
+        return `<div class="notice notice-${md.utils.escapeHtml(info)}">\n`;
+      } else {
+        // closing tag
+        return "</div>\n";
+      }
+    },
+  });
+}