improve README

README.md

@@ -16,8 +16,22 @@ If you can't or don't want to use `opam`, consult the [opam file] for build inst
 
 ## Quickstart
 
-```ocaml
-let () = TODO
+```shell-session
+$ curl https://osh.ocamlpro.com/badge\?label\=build\&color\=green\&status\=passing > badge.svg
+$ cat badge.svg
+<svg width="88.600000" height="20.000000" viewBox="0 0 886.000000 200" xmlns="http://www.w3.org/2000/svg" role="img" aria-label="build: passing">
+  <title>build: passing</title>
+  <g>
+    <rect fill="#2A2A2A" width="368.000000" height="200"/>
+    <rect fill="#3C1" x="368.000000" width="518.000000" height="200"/>
+  </g>
+  <g aria-hidden="true" fill="#fff" text-anchor="start" font-family="Verdana,DejaVu Sans,sans-serif" font-size="110">
+    <text x="60.000000" y="148" textLength="268.000000" fill="#000" opacity="0.1">build</text>
+    <text x="50.000000" y="138" textLength="268.000000">build</text>
+    <text x="423.000000" y="148" textLength="418.000000" fill="#000" opacity="0.1">passing</text>
+    <text x="413.000000" y="138" textLength="418.000000">passing</text>
+  </g>
+  </svg>
 ```
 
 For more, have a look at the [example] folder, at the [documentation] or at the [test suite].
@@ -28,6 +42,7 @@ For more, have a look at the [example] folder, at the [documentation] or at the
 - [CHANGELOG]
 
 [CHANGELOG]: ./CHANGES.md
+[documentation]: https://osh.ocamlpro.com
 [example]: ./example/
 [LICENSE]: ./LICENSE.md
 [opam file]: ./osh.opam