docs: Auto generate shape docs

Not keen on how it's currently run, open to suggestions on better ways.

.esbuild/docs.ts

@@ -0,0 +1,34 @@
+import { execFileSync } from 'child_process';
+import { build } from 'esbuild';
+import { rm } from 'fs/promises';
+import { generateLangium } from '../.build/generateLangium.js';
+import type { MermaidBuildOptions } from './util.js';
+import { defaultOptions, getBuildConfig } from './util.js';
+
+const buildDocs = async () => {
+  const option: MermaidBuildOptions = {
+    ...defaultOptions,
+    options: {
+      file: 'rendering-util/rendering-elements/shapes.cli.ts',
+      name: 'mermaid-shapes',
+      packageName: 'mermaid',
+    },
+  } as const;
+
+  await build({ ...getBuildConfig(option), splitting: false, sourcemap: false });
+};
+
+const handler = (e) => {
+  // eslint-disable-next-line no-console
+  console.error(e);
+  process.exit(1);
+};
+
+const main = async () => {
+  await generateLangium();
+  await buildDocs().catch(handler);
+  execFileSync('node', ['packages/mermaid/dist/mermaid-shapes.esm.mjs']);
+  await rm('packages/mermaid/dist/mermaid-shapes.esm.mjs');
+};
+
+void main();