Create new API category (#1123)

graphql.md

@@ -2,7 +2,7 @@
 title: GraphQL
 layout: 2017/sheet
 updated: 2017-09-23
-category: Databases
+category: API
 ---
 
 ## Intro

http-status.md

@@ -1,6 +1,6 @@
 ---
 title: HTTP Status
-category: HTTP
+category: API
 layout: 2017/sheet
 description: |
   List of HTTP Status codes and links to description.
@@ -111,4 +111,4 @@ WebDAV is an extension of HTTP that allows clients to perform remote Web content
 
  * <https://en.wikipedia.org/wiki/List_of_HTTP_status_codes>
  * <https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html>
- * <https://httpstatuses.com/>
+ * <https://httpstatuses.com/>

rest-api.md

@@ -2,6 +2,7 @@
 title: RESTful API
 updated: 2018-12-25
 layout: 2017/sheet
+category: API
 ---
 
 ### Status codes