Add npm package for the docgen-tool

Makefile

@@ -74,5 +74,6 @@ check-tidy: generate
 release:
 	@(VERSIONED_FILES="version.go \
 	npm-packages/cadence-parser/package.json \
-	npm-packages/cadence-language-server/package.json" \
+	npm-packages/cadence-language-server/package.json \
+	npm-packages/cadence-docgen/package.json" \
 	./bump-version.sh $(bump))

npm-packages/cadence-docgen/.gitignore

@@ -0,0 +1 @@
+dist

npm-packages/cadence-docgen/README.md

@@ -0,0 +1,30 @@
+# Cadence Documentation Generator
+
+The [Cadence](https://github.com/onflow/cadence) docgen tool compiled to WebAssembly and bundled as an NPM package,
+so it can be used in tools written in JavaScript.
+
+## Usage
+
+```js
+import {CadenceDocgen} from "@onflow/cadence-docgen"
+
+const docgen = await CadenceDocgen.create("cadence-docgen.wasm")
+
+const docs = docgen.generate(`
+  /// This is a simple function with a doc-comment.
+  pub fun hello() {
+  }
+`)
+```
+
+## Development
+
+- Building the docgen WASM binary:
+
+  ```sh
+  cd ../../tools/docgen/wasm/
+
+  GOARCH=wasm GOOS=js go build -o ../../../npm-packages/cadence-docgen/dist/cadence-docgen.wasm
+  ```
+
+<!-- Cannot build from current location due to: https://github.com/golang/go/issues/43733 -->

npm-packages/cadence-docgen/jest.config.js

@@ -0,0 +1,8 @@
+module.exports = {
+  testEnvironment: 'node',
+  "transform": {
+      "^.+\\.[tj]s$": "ts-jest"
+  },
+  setupFilesAfterEnv: [ './tests/setup.js' ],
+  testPathIgnorePatterns: ["/node_modules/", "/dist/"]
+};