Update CONTRIBUTING.md with instructions for new macs

CONTRIBUTING.md

@@ -31,7 +31,7 @@ Do the below OR if you prefer Docker, see the Docker Setup section
    * If you installed a Ruby version manager, when you cd into the project directory, let your version manager install the ruby version in `.ruby-version`
 3. Install the `bundler` package managers:
 ```
-gem install bundler
+gem install bundler -v 2.4.22
 ```
 4. Fork the repo (click the Fork button above), and clone your fork to your local machine. [Here's a GitHub tutorial](https://help.github.com/articles/fork-a-repo/)
 5. Install or start postgres.
@@ -40,6 +40,13 @@ gem install bundler
    * Rails relies on the `postgres` role existing, but this role is not always created in a Postgres installation. If you run into connection errors complaining that the `postgres` role is missing, you can create it with the command: `createuser -s -r postgres`
    * See this article if you get stuck on Ubuntu: https://www.digitalocean.com/community/tutorials/how-to-use-postgresql-with-your-ruby-on-rails-application-on-ubuntu-14-04
 6. Install all dependencies (including Rails):
+
+allow less strict function pointier types so that things can compile
+```
+bundle config build.nio4r --with-cflags="-Wno-error=incompatible-function-pointer-types"
+```
+then
+
 ```
 $ bundle install
 ```
@@ -65,6 +72,12 @@ If this step fails on Ubuntu, make sure that your postgres db is up and running
 and that you only have one postgres instance up: try `sudo lsof -i:5432`.
 You may need to use sudo to set your `/etc/postgresql/11/main/pg_hba.conf` file.
 IPv4 local connections should say `localhost` under ADDRESS and `trust` under METHOD.
+
+If this step fails on a Mac with Apple Silicon (the M chips) with `TypeError: unable to resolve type 'size_t'` , update ffi:
+```
+bundle update ffi
+```
+
 9.  Now you should be able to run tests locally, and they should all pass:
 ```
 $ bundle exec rake spec
@@ -73,8 +86,16 @@ $ bundle exec rake spec
 ### Steps to run arooo server locally
 
 1. `bundle exec rake populate:users` to set up dummy data
-1. `bundle exec rails server` don't forget to use http://localhost:3000 and not https
-1. `bundle exec rails console` Optional - useful for looking at and changing your local data)
+
+if you get `FATAL:  database "doubleunion_development" does not exist`, you need to create the database first:
+
+```
+  bundle exec rake db:create
+  bundle exec rake db:migrate
+```
+
+2. `bundle exec rails server` don't forget to use http://localhost:3000 and not https
+3. `bundle exec rails console` Optional - useful for looking at and changing your local data)
 
 ### Docker setup (optional)