docs(readme): add usage guide and more

README.md

@@ -1,2 +1,83 @@
 # sitemap-manager
 An easy way to create sitemaps!
+
+## Features
+Quick, Fast, And Beautiful!
+
+## Usage
+First run
+
+```shell
+$ npm i sitemap-manager --save
+or
+$ yarn add sitemap-manager
+```
+
+Then just try it:
+
+```js
+const { CreateSitemap, CreateIndexSitemap, CreateSitemapStylesheet } = require('sitemap-manager')
+const data = {/* data here */} //see more in scripts/test.js
+const siteURL = data.site.siteMetadata.siteUrl
+const pathPrefix = '/aaa/'
+
+// Create Sitemaps for each kind of pages.
+CreateSitemap(
+  path.resolve('./public/sitemap-articles.xml'), // The path of the file which will be generated.
+  pathPrefix, // Prefix of the path. If your site doesn't at the root of the domain,just try this.
+              // Example:
+              //   given path: /foo/
+              //   handled path: /aaa/foo/
+  siteURL, // The domain of your site.
+  data.postsQuery.edges, // Your data, shoud be an array
+  (data) => { return data.node.fields.slug }, // How to turn the data to a path
+)
+CreateSitemap(
+  path.resolve('./public/sitemap-logs.xml'),
+  pathPrefix,
+  siteURL,
+  data.postsQuery.edges,
+  (data) => { return data.node.fields.slug + 'changelog/' },
+)
+CreateSitemap(
+  path.resolve('./public/sitemap-tags.xml'),
+  pathPrefix,
+  siteURL,
+  data.tagsQuery.group,
+  (data) => { return `/tags/${data.fieldValue}/` },
+)
+CreateSitemap(
+  path.resolve('./public/sitemap-pages.xml'),
+  pathPrefix,
+  siteURL,
+  ['/pages/', '/settings/'],
+  (data) => { return data },
+)
+// Create an index for all sitemaps.
+CreateIndexSitemap(
+  path.resolve('./public/sitemap.xml'), // The path of the file which will be generated.
+  pathPrefix, // Prefix of the path. If your site doesn't at the root of the domain,just try this.
+  siteURL, // The domain of your site.
+  ['sitemap-pages.xml', 'sitemap-articles.xml', 'sitemap-logs.xml', 'sitemap-tags.xml'], // All the sitemaps should be here.
+)
+// Create the xml template file.
+// !IMPORTANT
+// Should be at the same dir as any other sitemaps.
+// E.g.
+// |
+// \
+//  aaa
+//  | sitemap.xml
+//  | sitemap.xsl
+//  | sitemap-artcles.xml
+//  | sitemap-logs.xml
+//    ...
+CreateSitemapStylesheet(
+  path.resolve('./public/sitemap.xsl'), // The path of the file which will be generated.
+  pathPrefix, // Prefix of the path. If your site doesn't at the root of the domain,just try this.
+  siteURL, // The domain of your site.
+)
+```
+
+## LICENSE
+MIT