extract HIP Contribution guide from readme

[samgutentag]

this content was previously in a docs contribution readme. should be placed with the HIP information and community governance pages

## Contibuting a Helium Improvement Proposal (HIP)

HIPs are modeled off Bitcoin Improvement Proposals (BIPs) and has become a standard in the crypto
world for open source development on both technical and economic issues.

HIPs serve several primiary functions:

- To make architecture changes
- To make economic and token changes
- To address cheating and security issues
- To address meta-governance

HIPs are not:

- Funding requests to The Helium Foundation
- Foundation treasury management

* **How do I submit a HIP?**: Open a 'pull request' in the HIP repository. DO NOT create an 'issue'.
  Your pull request signifies a HIP in draft status. HIPs in draft status should be discussed in
  #hip-general in the [Helium Official Community] (https://discord.gg/uTauMaJ2We). Draft HIPs will
  be addressed and managed by HIP editors. Please be sure to answer all of their questions
  appropriately. HIPs that do not work with HIP editors are seen as incomplete and are likely to be
  closed. Once your HIP is clear and has met all HIP requirements, HIPs are then open for deeper
  discussion with their own channels in the Helium Official Community. HIPs move to a vote after
  rough consensus that this HIP is appropriate for the community to vote on. There is never a
  guarantee your HIP will recieve a channel or move to a vote.

This project is intended to be a safe, welcoming space for collaboration, and contributors are
expected to adhere to the [Contributor Covenant Code of Conduct](http://contributor-covenant.org/).

Above all, thank you for taking the time to be a part of the Helium community.