docs: update to work out-of-the-box with current direnv version

A recent release of direnv disabled loading of .env files by
default. See direnv/direnv#911. Loading of
.env files can still be enabled by changing settings, but it's simpler
to provide documentation and an example that just works without
further changes beyond adding your personal settings / secrets.

.envrc.example

@@ -0,0 +1,11 @@
+export API_URL=
+export API_KEY=
+export GTFS_URL=
+export BUSLOC_URL=
+export POSTGRES_USERNAME=
+export POSTGRES_PASSWORD=
+export POSTGRES_HOSTNAME=
+export SWIFTLY_AUTHORIZATION_KEY=
+export SWIFTLY_REALTIME_VEHICLES_URL=
+export TRIP_UPDATES_URL=
+export ERL_FLAGS="+MIscs 2048"

.gitignore

@@ -46,6 +46,6 @@ node_modules
 *.terms
 
 # ENV variables
-.env
+.envrc
 
 .DS_Store

README.md

@@ -14,7 +14,7 @@ Doing development on Skate requires Elixir, Erlang, and node, as dsecribed in [.
 
 Skate also requires Postgres. If you don't already have Postgres installed, and you're on a Mac, [Postgres.app](https://postgresapp.com/downloads.html) is an easy way to get started. However, any Postgres instance to which you can connect and in which you have sufficient privileges should work.
 
-This guide assumes secrets and other application settings will be stored and passed in via a `.env` file. A blank `.env.example` file is included to use as a base. You can avoid having to prefix each command with an invocation of `env` by installing [direnv](https://direnv.net/).
+Secrets and other application settings are passed in via environment variables. To avoid having to set these manually in your local development environment, [direnv](https://direnv.net/) is strongly recommended. A `.envrc.example` file is provided to fill out; simply copy it over to `.envrc` and fill in the values, then follow the direnv documentation to load it.
 
 Quick setup: