set main branch to master for 'edit this page' links (#10447)

website/pages/docs/[[...page]].jsx

@@ -15,6 +15,7 @@ export default function DocsLayout(props) {
       subpath={subpath}
       order={order}
       staticProps={props}
+      mainBranch="master"
     />
   )
 }

website/pages/guides/[[...page]].jsx

@@ -15,6 +15,7 @@ export default function GuidesLayout(props) {
       subpath={subpath}
       order={order}
       staticProps={props}
+      mainBranch="master"
     />
   )
 }

website/pages/intro/[[...page]].jsx

@@ -15,6 +15,7 @@ export default function IntroLayout(props) {
       subpath={subpath}
       order={order}
       staticProps={props}
+      mainBranch="master"
     />
   )
 }