fix main readme TOC (#380)

Signed-off-by: Tihomir Surdilovic <[email protected]>

Author: tsurdilo

README.md

@@ -19,6 +19,7 @@ Cloud Native Sandbox level project on July 14, 2020.
 - [CNCF Landscape](#CNCF-Landscape)
 - [Releases](#Releases)
 - [SDKs](#SDKs)
+- [Runtime](#Runtime)
 - [Tooling](#Tooling)
 - [Community](#Community)
     - [Communication](#Communication)