docs: Add README for examples

packages/examples/README.md

@@ -0,0 +1,41 @@
+# @mermaid-js/examples
+
+The `@mermaid-js/examples` package contains a collection of examples used by tools like [mermaid.live](https://mermaid.live) to help users get started with new diagrams.
+
+You can duplicate an existing diagram example file, e.g., `packages/examples/src/examples/flowchart.ts`, and modify it with details specific to your diagram.
+
+Then, import the example in the `packages/examples/src/index.ts` file and add it to the `examples` array.
+
+Each diagram should have at least one example, which should be marked as the default. It's a good idea to add more examples to showcase different features of the diagram.
+
+## Usage
+
+```bash
+pnpm add @mermaid-js/examples
+```
+
+A sample usage of the package in mermaid.live, to get the default example for every diagram type:
+
+```ts
+import { diagramData } from '@mermaid-js/examples';
+
+type DiagramDefinition = (typeof diagramData)[number];
+
+const isValidDiagram = (diagram: DiagramDefinition): diagram is Required<DiagramDefinition> => {
+  return Boolean(diagram.name && diagram.examples && diagram.examples.length > 0);
+};
+
+export const getSampleDiagrams = () => {
+  const diagrams = diagramData
+    .filter((d) => isValidDiagram(d))
+    .map(({ examples, ...rest }) => ({
+      ...rest,
+      example: examples?.filter(({ isDefault }) => isDefault)[0],
+    }));
+  const examples: Record<string, string> = {};
+  for (const diagram of diagrams) {
+    examples[diagram.name.replace(/ (Diagram|Chart|Graph)/, '')] = diagram.example.code;
+  }
+  return examples;
+};
+```