fix(Package): Move @types/ws back to prod dependencies

See note in README for why.

README.md

@@ -95,3 +95,10 @@ There is a NPM script, `cli:debug`, that can be useful for debugging the CLI, fo
 ```bash
 npm run cli:debug -- compile test.md
 ```
+
+## FAQ
+
+#### Why is `@types/ws` a production dependency?
+
+This package has several dependents e.g `@stencila/basha`. If `@types/ws` is not installed as a production dependency, when you try to build dependent packages, you get the error "Cannot find type definition file for 'ws'.". By having it as a production dependency here, each dependent package does not have to install it
+as a development dependency.

package.json

@@ -45,7 +45,6 @@
     "@types/mkdirp": "0.5.2",
     "@types/nanoid": "2.1.0",
     "@types/split2": "2.1.6",
-    "@types/ws": "6.0.4",
     "depcheck": "0.9.1",
     "jest": "24.9.0",
     "lolex": "5.1.2",
@@ -66,6 +65,7 @@
     "@stencila/configa": "^0.4.0",
     "@stencila/logga": "^2.1.0",
     "@stencila/schema": "^0.32.0",
+    "@types/ws": "6.0.4",
     "ajv": "^6.10.2",
     "chalk": "^3.0.0",
     "cli-highlight": "^2.1.4",