Update CONTRIBUTING.md (#185)

* Update CONTRIBUTING.md

Update with description of DIP and DIP process

* Update CONTRIBUTING.md

Fix typo

Author: sstruble

CONTRIBUTING.md

@@ -1,3 +1,9 @@
 # CONTRIBUTING
 
 For contributing guidelines see the [Project Liberty Contributing Guidelines](https://github.com/LibertyDSNP/meta/blob/main/CONTRIBUTING.md).
+
+# DSNP Improvement Proposal (DIP) and DIP Process
+
+A DIP is any update that would materially change the DSNP specification, as opposed to non-material changes, like fixing spelling errors. There is a pre-configured issue template for creating DIPs as part of the DSNP Specification repository.
+
+As the DSNP protocol matures, we will create a DIP governance and approval process that's appropriate to the evolving needs of the community, following well-established open source development practices. For now, we simply discuss the merits of the suggested change and approve or disapprove based on a rough consensus.