docs: Fix anchor for osbuilder
The HTML anchor generated by github for "osbuilder" wasn't working, so
removed the slash from the title.
* [Documentation](#documentation)
* [Test code](#test-code)
* [Utilities](#utilities)
- * [O/S builder](#o/s-builder)
+ * [OS builder](#os-builder)
* [Web content](#web-content)
---
@@ -112,7 +112,7 @@ as the component it tests).
### Utilities
-#### O/S builder
+#### OS builder
The [osbuilder](https://github.com/kata-containers/osbuilder) tool can create
a rootfs and a "mini O/S" image. This image is used by the hypervisor to setup
