Fix typos in stale.yml (apollographql#821)

Author: cesarsolorzano

.github/stale.yml

@@ -9,7 +9,7 @@ exemptLables:
   - enhancement
 # text of the comment when marking issue as stale
 markComment: >
-  This issue has been automatically marked as stale becuase it has not had recent activity. It will be closed if not further activity occurs. Thank you for your contributions to React Apollo!
+  This issue has been automatically marked as stale because it has not had recent activity. It will be closed if not further activity occurs. Thank you for your contributions to React Apollo!
 # text of the comment when closing an issue
 closeComment: >
-  This issue has been automatically closed because it has not had recent activity after being marked as stale. If you belive this issue is still a problem or should be reopened, please reopen it! Thank you fo ryour contributions to React Apollo!
+  This issue has been automatically closed because it has not had recent activity after being marked as stale. If you belive this issue is still a problem or should be reopened, please reopen it! Thank you for your contributions to React Apollo!