Create documentation for how to run our site with jekyll

### Overview
Sometimes docker does not work, so we should have some documentation about how to use jekyll.

### Action Items
- [ ] We are currently in the process of moving the old wiki to the new [website-wiki repo](https://github.com/hackforla/website-wiki), so we will not be making any changes or additions to the old wiki at this time. Thus, we will be adding wiki content through a different process now. Please read [How to Contribute to the Wiki](https://github.com/hackforla/website/wiki/How-to-Contribute-to-the-Wiki)
- [ ] create a wiki article with the necessary steps
- [ ] test it out
- [ ] Make sure it is compatible with all systems (Mac, Windows, Iinux)
- [ ] share with dev team and have people review it
- [ ] close this issue

### Plan
- Create a Gemfile.example (Gemfile is in .gitignore. See comments below for discussions about Gemfile and why it can't be checked in)
- create separate markdown on deploying in jekyll. Indicate in the document that if you run into issues, support may be limited and you may be asked to try Docker.
- Link to this file from contributing.md with same caveat as above.

### Instruction
- downloading [ruby](https://rubyinstaller.org/) and [jekyll](https://jekyllrb.com/docs/installation/) for windows
- other instructions for mac
- cd into directory w website repo
- cp Gemfile.example Gemfile
- type `bundle install`
- type `jekyll serve`