📝 Add basic usage information

Author: Sergei Orlov

README.md

@@ -7,6 +7,102 @@
  Gatsby Source Plugin Notion API
 </h1>
 
+[![Maintainability](https://api.codeclimate.com/v1/badges/669015699caf1728d984/maintainability)](https://codeclimate.com/github/orlowdev/gatsby-source-notion-api/maintainability)
+
+[![code style: prettier](https://img.shields.io/badge/code_style-prettier-ff69b4.svg)](https://github.com/prettier/prettier)
+[![versioning: or-release](https://img.shields.io/badge/versioning-%7C%7Cr-E76D83.svg)](https://github.com/orlowdev/or-release)
+
 Gatsby source plugin for working with official [Notion](https://notion.so) API.
 
-## 🚧 Work in progress
+## 🚧 It's a work in progress
+
+This is a source plugin for pulling content into Gatsby from official public Notion API (currently
+in beta). With this plugin, you will be able to query your Notion pages in Gatsby using GraphQL.
+
+[Notion API Reference](https://developers.notion.com/reference/intro)
+
+An example (...coming soon)
+
+## Install
+
+```sh
+yarn add gatsby-source-notion-api
+```
+
+or
+
+```sh
+npm install --save gatsby-source-notion-api
+```
+
+## How to use
+
+Before using this plugin, make sure you
+
+1. Created a Notion integration (sign in to Notion, go to `Settings & Memberships` → `Integrations`
+ → `Develop your own integrations`,
+ [short link to the Integrations creation section](https://www.notion.so/my-integrations)). It's
+ OK to use an internal one. Don't forget to copy the token.
+2. Go to the database you want to have access to and share it with the integration (`Share` → Select
+ the integration in the `Invite` dropdown). Don't forget the database in the URL. It's a series of
+ characters after the last slash and before the question mark. Here's a reference:
+ https://www.notion.so/{USER}/**{DATABASE_ID}**?{someotherirrelevantstuff}
+3. Then add this to your `gatsby-config.json`:
+
+```javascript
+plugins: [
+{
+resolve: `gatsby-source-notion-api`,
+options: {
+token: `$INTEGRATION_TOKEN`,
+databaseId: `$DATABASE_ID`,
+},
+},
+// ...
+]
+```
+
+## Configuration options
+
+`token` [string][required]
+
+Integration token.
+
+`databaseId` [string][required]
+
+The identifier of the database you want to get pages from. The integration identified by provided
+token must have access to the database with given id.
+
+## How to query for nodes
+
+You can query for pages with `notion` or grab all of them with `allNotion`. The raw content of the
+page is available under `raw` property.
+
+### Query for all nodes
+
+```graphql
+query {
+allNotion {
+edges {
+node {
+raw
+}
+}
+}
+}
+```
+
+## Current state
+
+- Due to the fact that Notion API only appeared recently, and it is still in beta, some blocks are
+ marked "unsupported". Among others, images cannot be fetched for now
+- Currently, `gatsby-source-notion-api` can only work with one provided database. In further
+ releases, all databases reachable by the Integration will be available for querying
+- Nested blocks are currently skipped. E.g. if a list item has a nested sublist, it's contents will
+ be omitted. This will be fixed in the nearest releases
+- Only raw content is available. Raw meaning whatever Notion returns. Further releases will aim at
+ providing a more convenient data format apart from the raw one
+
+## 🎉 You did it
+
+Thanks for reaching to the end of the readme!