Prop 559: Change Commonwealth Posting Requirement to Discourse

This proposal would change the canonical location for Osmosis governance discussion from Commonwealth to the new Discourse forum.

## Background
Osmosis Governance currently has a waiting period before a proposal is posted on chain to allow feedback and iteration by the community before the text is frozen.

This was first implemented in Proposal 199 as a three-day requirement and later expanded upon in Proposal 438 to clarify times when these three days were not required or longer was required to be able to review more complex proposals.

Both proposals specified that threads must be posted on Commonwealth as the canonical location for Osmosis governance discussions.

An alternative Discourse forum has been established due to reported issues with Commonwealth accessibility.

This can be found at the following link:

https://community.osmosis.zone/

This proposal would maintain all requirements in Proposal 438, but replaces any references to Commonwealth with Discourse.

This ensures that there remains a single location for Osmosis governance discussion so that discussion is not fragmented whilst lowering the barrier to entry for new participants.

Commonwealth Thread: https://commonwealth.im/osmosis/discussion/12054-change-commonwealth-posting-requirement-to-discourse