replace Gitter references with Slack #minicomp-wax

.gitignore

@@ -6,6 +6,7 @@ _site
 
 # system things
 .DS_Store
+.idea/
 
 # ruby things
 Gemfile.lock

README.md

@@ -5,7 +5,7 @@
 [![Build Status](https://travis-ci.com/minicomp/wax.svg?branch=main)](https://travis-ci.com/minicomp/wax)
 [![Depfu](https://badges.depfu.com/badges/9d4da973f2cd2680c11ca34738c2dfb2/overview.svg)](https://depfu.com/github/minicomp/wax?project_id=10550)
 [![Gem Downloads](https://img.shields.io/gem/dt/wax_theme.svg?color=046d0b)](https://badge.fury.io/rb/wax_theme)
-[![Join the chat at https://gitter.im/minicomp/wax](https://badges.gitter.im/minicomp/wax.svg)](https://gitter.im/minicomp/wax?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+[![Join the chat the minicomp-wax channel of the Code4Lib Slack](https://img.shields.io/badge/Slack-%23minicomp--wax-brightgreen.svg)](https://docs.google.com/forms/d/e/1FAIpQLSeD77mBp0Y13mFePF8UmDwFrlbxNx3VttEjz_3dgglJeK-Zbg/viewform?c=0&w=1)
 ![License](https://img.shields.io/github/license/minicomp/wax_tasks.svg?color=c6a1e0)
 
 
@@ -122,4 +122,4 @@ You can exit the container at any time with `$ exit`, which will automatically s
 
 # Contributing
 
-We welcome contributions to Wax, including bug reports and feature requests (submitted as [Issues](https://github.com/minicomp/wax/issues)), code contributions (submitted as [Pull Requests](https://github.com/minicomp/wax/pulls)), and documentation updates (submitted however!) Not sure where to start? Feel free to get in touch via [GitHub issue](https://github.com/minicomp/wax/issues) or [Gitter chat](https://gitter.im/minicomp/wax).
+We welcome contributions to Wax, including bug reports and feature requests (submitted as [Issues](https://github.com/minicomp/wax/issues)), code contributions (submitted as [Pull Requests](https://github.com/minicomp/wax/pulls)), and documentation updates (submitted however!) Not sure where to start? Feel free to get in touch via [GitHub issue](https://github.com/minicomp/wax/issues) or grab an invite to join the conversation on the `#minicomp-wax` channel of the [Code4Lib Slack](https://docs.google.com/forms/d/e/1FAIpQLSeD77mBp0Y13mFePF8UmDwFrlbxNx3VttEjz_3dgglJeK-Zbg/viewform?c=0&w=1).