Apply suggestions from code review

Author: jfy133

.github/ISSUE_TEMPLATE/new_rfc.yml

@@ -1,7 +1,7 @@
 name: New RFC proposal
 description: Propose a major new functionality for incorporation into nf-core
-title: "New RFC: <short sentence descibing prosposal>"
-labels: "RFC,proposed"
+title: "New RFC: <short sentence describing proposal>"
+labels: "new-rfc,proposed"
 projects: nf-core/128
 assignees:
   - nf-core/core