Update CONTRIBUTING.md

Author: parispittman

CONTRIBUTING.md

@@ -13,7 +13,9 @@ This repository is not your standard codebase. It houses Swift evolution proposa
 ### New proposals pull requests or major modifications 
 New proposals that follow the [Swift evolution process](process.md) can be submitted as a pull request after the pitch process in the [evolution forums](https://forums.swift.org/c/evolution/pitches/5).
 
-Substantive changes to:
-- existing proposals should only be made with the permission of the proposal authors.  Substantive changes to a proposal in the Accepted or Rejected states are discouraged and require the approval of the appropriate evolution workgroup.  Substantive changes to a proposal in the Active Review state require the approval of the appropriate evolution workgroup and should be advertised in the review thread.
-- change vision documents require the approval of the appropriate evolution workgroup.
-- documented evolution process require the approval of the Core Team.
+#### Substantive changes
+- changes to existing proposals should only be made with the permission of the proposal authors.
+- changes to a proposal in the Accepted or Rejected states are discouraged and require the approval of the appropriate evolution workgroup.
+- changes to a proposal in the Active Review state require the approval of the appropriate evolution workgroup and should be advertised in the review thread.
+- changes to vision documents require the approval of the appropriate evolution workgroup.
+- changes to documented evolution process require the approval of the Core Team.