Don't add a dummy API key to every new Rails app

Every new Rails app is currently generated with
`Rails.application.secrets[:api_key]` set to `123`.

This comes from a line in `config/secrets.yml` that, in my opinion,
should be left commented out to only serve as a syntax example, rather
than being actually set in every Rails app.

Additionally, we might want to give a better example than `123`, since
in the same file we are suggesting to

> Make sure the secret is at least 30 characters and all random,
> no regular words or you'll be exposed to dictionary attacks.

The result of this commit is that `config/secrets.yml` will include something like:

```yaml
 # Shared secrets are available across all environments.

 # shared:
 #   api_key: f56930851993982510d5bd9236f4108f6fe7c15448f1c6923a51872e0dbae1a24d274b318abb6518b540dfb51079c61640885f607467e5ed1053849be7587d61
```

rather than this:

```yaml
 # Shared secrets are available across all environments.

 shared:
   api_key: 123
```

1 files changed, 2 insertions, 2 deletions

diff --git a/railties/lib/rails/generators/rails/app/templates/config/secrets.yml b/railties/lib/rails/generators/rails/app/templates/config/secrets.yml
index 816efcc5b1..ea9d47396c 100644
--- a/railties/lib/rails/generators/rails/app/templates/config/secrets.yml
+++ b/railties/lib/rails/generators/rails/app/templates/config/secrets.yml
@@ -12,8 +12,8 @@
 
 # Shared secrets are available across all environments.
 
-shared:
-  api_key: 123
+# shared:
+#   api_key: a1B2c3D4e5F6
 
 # Environmental secrets are only available for that specific environment.