Update README.md on main to match develop

Author: amiller-ims

README.md

@@ -1,9 +1,12 @@
 # openbadges-specification
 ## Specification documents related to Open Badges
-The published version of Open Badges 2.0 is in master and develop. Version 2.1 is only in develop until Final.
+The published version of Open Badges 2.0 is in main and develop. Version 2.1 is only in develop until Final.
+
+## Proposals
+For information about how to propose a new feature or material change to the specification, please see `proposals/README.md`.
 
 ## Branches
-* __master__: stable, deployable branch that stores the official release history including releases designated as Candidate Final Public.
+* __main__: stable, deployable branch that stores the official release history including releases designated as Candidate Final Public.
 * __develop__: unstable development branch. Current work that targets a future release is merged into this branch.
 * __feature/new-feature-name__: unstable feature branch. Work that may be approved for future release will be developed in here and branched from __develop__.
 
@@ -17,4 +20,4 @@ Please follow these steps to contribute a change to the openbadges-specification
 1. Make your changes aware to the workgroup by raising them during a workgroup meeting. This will typically involve putting the topic on the agenda by way of the workgroup chair and/or an IMS Global staff member.
 1. Pull request or general merges into the __develop__ branch generally require workgroup approval unless IMS Staff or the workgroup chair indicate otherwise.
 
-For information on how to use GitHub within IMS Global, please see: [Spec Central](https://github.com/IMSGlobal/spec-central/blob/master/github-getting-started.md).
+IMS Contributing Members may access [Spec Central](https://github.com/IMSGlobal/spec-central/blob/master/github-getting-started.md) for further details about using GitHub for IMS activities.