update membership-request issue template (#53)

Signed-off-by: Kevin Wang <[email protected]>

.github/ISSUE_TEMPLATE/membership-request.md

@@ -17,13 +17,17 @@ assignees: ''
 
 - [ ] I have reviewed the [community membership guidelines]
 - [ ] I have joined in the community [mailing list] and [slack]
+- [ ] I have watched kubeedge/kubeedge on GitHub to subscribe updates (My account appears in the [watchers list])
 - [ ] I have enabled [two-factor authentication] on my GitHub account
 - [ ] I am actively contributing to 1 or more KubeEdge subprojects
 - [ ] I have spoken to my sponsors ahead of this application, and they have agreed to sponsor my application
 - [ ] I have checked my affiliation in [devstats] (if it's not correct, please fix in [cncf/gitdm])
 
 ## Sponsors
-<!-- List github handle of your sponsors -->
+<!--
+  List github handle of your sponsors.
+  Two sponsors is enough, but better from different companies/organizations.
+-->
 
 ## List of contributions to the KubeEdge project
 - PRs reviewed / authored:
@@ -32,9 +36,12 @@ assignees: ''
 
 - Issues responded to:
 
+
+<!-- Please don't edit the following lines -->
 [community membership guidelines]: https://github.com/kubeedge/community/blob/master/community-membership.md
 [mailing list]: https://groups.google.com/forum/#!forum/kubeedge
 [slack]: https://kubeedge.slack.com/
+[watchers list]: https://github.com/kubeedge/kubeedge/watchers
 [two-factor authentication]: https://help.github.com/en/github/authenticating-to-github/about-two-factor-authentication
 [devstats]: https://kubeedge.devstats.cncf.io/d/56/company-commits-table?orgId=1
 [cncf/gitdm]: https://github.com/cncf/gitdm#addingupdating-affiliation