Update project documentation for installing Ruby (#74)

.gitignore

@@ -1,3 +1,4 @@
 .DS_Store
 _site
 Gemfile.lock
+.bundle

Gemfile

@@ -1,2 +1,4 @@
 source 'https://rubygems.org'
 gem 'github-pages', group: :jekyll_plugins
+
+gem "webrick", "~> 1.8"

contributing.md

@@ -57,19 +57,37 @@ More information on grip [here](https://github.com/joeyespo/grip).
 
 1. If you don't have Ruby installed, install Ruby 2.1.0 or higher from [here](https://www.ruby-lang.org/en/downloads/).
 
+For Debian 10, you can do this:
+```bash
+sudo apt-get install ruby ruby-dev make gcc g++ zlib1g zlib1g-dev git
+```
+
 2. Using a command shell go to the folder that contains the cloned copy of the repository on your computer and type these commands to install Jekyll:
 
 ```bash
 gem install bundler
 bundle install
 ```
 
+On a Debian 10 machine where you don't have access to system resources, you can do this instead:
+
+```bash
+gem install bundler --user-install
+~/.gem/ruby/2.5.0/bin/bundle install --path ~/.gem/
+```
+
 3. Run Jekyll like this (from the same folder as step 2). This
    will also compile any changes you make to Jekyll files and
    send them to the target web site:
 
 ```bash
 bundle exec jekyll serve
+```
+
+For the Debian 10 install above, the command to run Jekyll is:
+
+```bash
+~/.gem/ruby/2.5.0/bin/bundle exec jekyll serve
 ```
 
    More information on Jekyll [here](https://help.github.com/articles/setting-up-your-github-pages-site-locally-with-jekyll/).

requirements.yml

@@ -0,0 +1,8 @@
+# conda requirements file to create virtual environment for INTERMAGNET web site
+# use like this: conda env create -f requirements.yml
+name: intermagnet.github.io
+dependencies:
+ - python=3.6
+ - pip:
+   - grip==4.5.2
+