README: remove outdated link

Signed-off-by: gatecat <[email protected]>

Author: gatecat

README.md

@@ -1,7 +1,5 @@
 # GF130 Test Chip Repo
 
-[Functional Spec](https://docs.google.com/document/d/1OfJ8b6-Y-HwSge2IwM3l8fVJmEs0IDzf/edit)
-
 ## VS Code debugger
 
 * Download the [latest VSIX package](https://github.com/ChipFlow/rtl-debugger/releases/tag/latest) for the extension.