Adds sitemap docs (#78)

README.md

@@ -66,3 +66,89 @@ Once instantiated Amphora Search will begin managing it's own internal indices,
 ## Contributing
 
 Want a feature or find a bug? Create an issue or a PR and someone will get on it.
+
+## Sitemaps
+
+If the `sitemaps` configuration option is set to `true`, Amphora Search will automatically stream basic text and xml sitemaps at `/_sitemaps/sitemap.txt` and `/_sitemaps/sitemap.xml` using data from the `pages` index.
+
+By default these endpoints will show pages first published in the current year; you can specify a different year with the `year` query param e.g. `?year=2017`.
+
+### Custom Sitemap
+
+If you would like to customize your sitemaps, add a mapping and handler for a `sitemap-entries` index to your Clay installation. Amphora Search will automatically use this index to populate the sitemaps. For the XML sitemap, Amphora Search simply converts the Elasticsearch docs to XML using `xmljs`, so a mapping like this:
+
+```
+_doc:
+  properties:
+    loc:
+      type: keyword
+    site:
+      type: keyword
+    lastmod:
+      type: date
+```
+
+...might result in a document like this:
+
+```
+{
+  "site": "foo",
+  "loc": "http://bar.com/some-article",
+  "lastmod": "2018-03-15T14:15:04.726Z"
+}
+```
+
+...which would produce a sitemap entry like this:
+
+```
+<url>
+  <loc>
+    http://bar.com/some-article
+  </loc>
+  <lastmod>2018-03-15T14:15:04.726Z</lastmod>
+</url>
+```
+
+Note that the `site` mapping property is reserved for the slug of the site that the entry should appear in and doesn't appear in the resulting XML.
+
+Currently, there is no endpoint for listing all the sitemaps from each year.
+
+### News Sitemap
+
+If you create a mapping and handler for a `news-sitemap-entries` index, Amphora Search will also stream news sitemap entries at `/_sitemaps/news.xml` using data from that index. Per Google's guidelines, it will only stream articles from the last two days.
+
+Example mapping:
+
+```
+_doc:
+  properties:
+    site:
+      type: keyword
+    loc:
+      type: keyword
+    lastmod:
+      type: date
+    news:news:
+      type: object
+      dynamic: false
+      properties:
+        news:publication:
+          type: object
+          properties:
+            news:name:
+              type: keyword
+            news:language:
+              type: keyword
+        news:publication_date:
+          type: date
+        news:title:
+          type: keyword
+        news:language:
+          type: keyword
+        news:keywords:
+          type: keyword
+        news:tags:
+          type: keyword
+```
+
+Again, the `site` mapping property is reserved for the slug of the site that the entry should appear in and does not appear in the resulting XML.