minor grammar edit (#283)

Author: EvaMaeRey

doc/_quarto.yml

@@ -20,7 +20,7 @@ website:
   announcement:
     icon: info-circle
     dismissable: true
-    content: "ggsql is still in early development and all functionality are subject to change"
+    content: "ggsql is still in early development and all functionality is subject to change"
     type: primary
     position: below-navbar
   twitter-card: