Fix link for filing issues on ex org.eclipse.mylyn.docs components

[olberger]

https://github.com/eclipse-mylyn/org.eclipse.mylyn.docs/issues is read-only now.

However, instructions still point to it in:

.github/profile/README.md

Line 24 in 9db531d

- https://github.com/eclipse-mylyn/org.eclipse.mylyn.docs/issues

This is probably interesting in the context of #35

Thanks in advance.