Fix minor errors in ISSUES.md

?Stack Overflow? ref.: <tensorflow/docs#406>

PiperOrigin-RevId: 251500200

ISSUES.md

@@ -5,5 +5,5 @@ out. 3. The issue should be related to the repo it is created in.
 
 **Here's why we have this policy:** We want to focus on the work that benefits
 the whole community, e.g., fixing bugs and adding features. Individual support
-should be seeked on StackOverflow or other non-GitHub channels. It helps us to
+should be sought on Stack Overflow or other non-GitHub channels. It helps us to
 address bugs and feature requests in a timely manner.