API Specifications Documentation Update (#21416)

* updating as v2 is now out and making it less repetitive

* Update api-specification.md

docs/docs/api-specification.md

@@ -4,7 +4,7 @@ title: API Specification
 
 Gatsby's APIs are tailored conceptually to some extent after React.js to improve the coherence between the two systems.
 
-The two top priorities of the API are a) enable a broad and robust plugin ecosystem and b) on top of that a broad and robust theme ecosystem (themes are on the back burner btw until after v1 comes out).
+The two top priorities of the API are a) enable a broad and robust plugin ecosystem and b) on top of that a broad and robust theme ecosystem.
 
 ## Prerequisites