docs: add slack and meeting info (#289)

Co-authored-by: Sertaç Özercan <852750+sozercan@users.noreply.github.com>

README.md

@@ -48,4 +48,10 @@ This approach is motivated by the core principles of making direct container pat
 
 For more details refer to the [full documentation](https://project-copacetic.github.io/copacetic/).
 
+## Contributing
+There are several ways to get involved:
+* Join the [mailing list](https://groups.google.com/g/project-copa) to get notifications for releases, security announcements, etc.
+* Join the [biweekly community meetings](https://docs.google.com/document/d/1QdskbeCtgKcdWYHI6EXkLFxyzTCyVT6e8MgB3CaAhWI/edit#heading=h.294j02tlxam) to discuss development, issues, use cases, etc.
+* Join the `#copa` channel on the [OCI Slack](https://communityinviter.com/apps/opencontainers/join-the-oci-community)
 
+The project welcomes contributions and suggestions that abide by the [Code of Conduct](./CODE_OF_CONDUCT.md)

website/docs/contributing.md

@@ -7,6 +7,9 @@ Welcome! We are very happy to accept community contributions to the project, whe
 ## Bi-Weekly Community Meeting
 A great way to get started is to join our bi-weekly community meeting. The meeting is held every other Monday from 1:30pm PT - 2:15pm PT. You can find the agenda and links to join [here](https://docs.google.com/document/d/1QdskbeCtgKcdWYHI6EXkLFxyzTCyVT6e8MgB3CaAhWI/edit?usp=sharing)
 
+## Slack
+To discuss issues with Copa, features, or development, you can join the `#copa` channel on the [OCI Slack](https://communityinviter.com/apps/opencontainers/join-the-oci-community).
+
 ## Contributing Issues
 
 Before opening any new issues, please search our [existing GitHub issues](https://github.com/project-copacetic/copacetic/issues) to check if your bug or suggestion has already been filed. If such an issue already exists, we recommend adding your comments and perspective to that existing issue instead.

website/versioned_docs/version-v0.3.x/contributing.md

@@ -7,6 +7,9 @@ Welcome! We are very happy to accept community contributions to the project, whe
 ## Bi-Weekly Community Meeting
 A great way to get started is to join our bi-weekly community meeting. The meeting is held every other Monday from 1:30pm PT - 2:15pm PT. You can find the agenda and links to join [here](https://docs.google.com/document/d/1QdskbeCtgKcdWYHI6EXkLFxyzTCyVT6e8MgB3CaAhWI/edit?usp=sharing)
 
+## Slack
+To discuss issues with Copa, features, or development, you can join the `#copa` channel on the [OCI Slack](https://communityinviter.com/apps/opencontainers/join-the-oci-community).
+
 ## Contributing Issues
 
 Before opening any new issues, please search our [existing GitHub issues](https://github.com/project-copacetic/copacetic/issues) to check if your bug or suggestion has already been filed. If such an issue already exists, we recommend adding your comments and perspective to that existing issue instead.

website/versioned_docs/version-v0.4.x/contributing.md

@@ -7,6 +7,9 @@ Welcome! We are very happy to accept community contributions to the project, whe
 ## Bi-Weekly Community Meeting
 A great way to get started is to join our bi-weekly community meeting. The meeting is held every other Monday from 1:30pm PT - 2:15pm PT. You can find the agenda and links to join [here](https://docs.google.com/document/d/1QdskbeCtgKcdWYHI6EXkLFxyzTCyVT6e8MgB3CaAhWI/edit?usp=sharing)
 
+## Slack
+To discuss issues with Copa, features, or development, you can join the `#copa` channel on the [OCI Slack](https://communityinviter.com/apps/opencontainers/join-the-oci-community).
+
 ## Contributing Issues
 
 Before opening any new issues, please search our [existing GitHub issues](https://github.com/project-copacetic/copacetic/issues) to check if your bug or suggestion has already been filed. If such an issue already exists, we recommend adding your comments and perspective to that existing issue instead.