Fix broken links in project/README.md

Related to https://github.com/moby/moby/pull/37104,
`RELEASE-CHECKLIST.md` has been removed by this PR

Signed-off-by: Lei Jitang <leijitang@outlook.com>

project/README.md

@@ -11,7 +11,7 @@ If you're a *maintainer* or aspiring maintainer, you should read [MAINTAINERS](.
 
 If you're a *packager* or aspiring packager, you should read [PACKAGERS.md](./PACKAGERS.md).
 
-If you're a maintainer in charge of a *release*, you should read [RELEASE-CHECKLIST.md](./RELEASE-CHECKLIST.md).
+If you're a maintainer in charge of a *release*, you should read [RELEASE-PROCESS.md](./RELEASE-PROCESS.md).
 
 ## Roadmap