update installation and usage instructions

README.md

@@ -15,22 +15,25 @@ Protobuf-First GraphQL Schemas with [GraphQL Nexus](https://nexusjs.org/)
 
 ## Installation
 
-```
-yarn add nexus graphql
+```sh
+yarn add nexus graphql  # required as a peer dependency
 yarn add --dev protoc-gen-nexus
 
 # if you generate code with `protoc --js_out`
-yarn add @proto-nexus/google-protobuf
+yarn add @proto-nexus/google-protobuf \
+  google-protobuf @types/google-protobuf  # required as a peer dependency
 
 # if you generate code with protobufjs
-yarn add @proto-nexus/protobufjs
+yarn add @proto-nexus/protobufjs \
+  protobufjs  # required as a peer dependency
 ```
 
 ## Usage
+### Generate GraphQL Types from Protobuf IDL
 
 To generate Nexus type definitions from `.proto` files, you need to invoke following command:
 
-```
+```sh
 protoc \
   -I ./node_modules/protoc-gen-nexus/include \
   -I <YOUR_PROTO_PATH> \
@@ -40,8 +43,57 @@ protoc \
   path/to/file.proto
 ```
 
-If you generate code with protobufjs, add `use_protobufjs` to `nexus_opt`
+#### with protobufjs
+
+proto-nexus supports protobufjs with static code generated by [protobufjs CLI](https://github.com/protobufjs/protobuf.js#command-line).
+
+```sh
+# `target`, `wrap` and `force-message` options are required.
+# An output file name must be `index.js`.
+pbjs \
+  --target static-module \
+  --wrap commonjs \
+  --force-message \
+  --path <YOUR_PROTO_PATH> \
+  --out "<DIST_DIR>/index.js" \
+  path/to/package/*.proto
 
+# An output file name must be `index.d.ts`
+pbts --out "<DIST_DIR>/index.d.ts" "<DIST_DIR>/index.js"
 ```
+
+And `protoc-gen-nexus` requires `use_protobufjs` option.
+
+```sh
   --nexus_opt="import_prefix=<YOUR_PROTO_PATH_OR_PACKAGE>,use_protobufjs" \
 ```
+
+
+### Make schema
+See also [Best Practices - GraphQL Nexus](https://nexusjs.org/docs/guides/best-practices#consistent-file-structure-for-graphql-type-imports).
+
+```typescript
+// src/schema/types/index.ts
+
+// Export generated types
+export * from "./path/to/generated_types/...";
+export * from "./path/to/generated_types/...";
+// ...
+```
+
+When `makeSchema`, `abstractTypeStrategies` must have `isTypeOf: true`.
+
+```typescript
+import { makeSchema } from "nexus";
+import * as allTypes from "./schema/types";
+
+export const schema = makeSchema({
+  types: alltypes,
+  output: { /* ... */ },
+  features: {
+    abstractTypeStrategies: {
+      isTypeOf: true,
+    },
+  },
+})
+```