docs(readme): promote auto_source feature & fix yaml parsing in examples

Author: gildesmarais

README.md

@@ -6,6 +6,7 @@ This web application scrapes websites to build and deliver RSS 2.0 feeds.
 
 **Features:**
 
+- Provides stable URLs for feeds generated by automatic sourcing.
 - [Create your custom feeds](#how-to-build-your-rss-feeds)!
 - Comes with plenty of [included configs](https://github.com/html2rss/html2rss-configs) out of the box.
 - Handles request caching.
@@ -48,7 +49,7 @@ services:
       RACK_ENV: production
       HEALTH_CHECK_USERNAME: health
       HEALTH_CHECK_PASSWORD: please-set-YOUR-OWN-veeeeeery-l0ng-aNd-h4rd-to-gue55-Passw0rd!
-      # AUTO_SOURCE_ENABLED: true
+      # AUTO_SOURCE_ENABLED: 'true'
       # AUTO_SOURCE_USERNAME: foobar
       # AUTO_SOURCE_PASSWORD: A-Unique-And-Long-Password-For-Your-Own-Instance
       ## to allow just requests originating from the local host
@@ -83,7 +84,7 @@ To enable the `auto_source` feature, comment in the env variables in the `docker
 ```yaml
 environment:
   ## … snip ✁
-  AUTO_SOURCE_ENABLED: true
+  AUTO_SOURCE_ENABLED: "true"
   AUTO_SOURCE_USERNAME: foobar
   AUTO_SOURCE_PASSWORD: A-Unique-And-Long-Password-For-Your-Own-Instance
   ## to allow just requests originating from the local host
@@ -93,7 +94,7 @@ environment:
   ## … snap ✃
 ```
 
-Restart the container and open <http://127.0.0.1:3000/auto_source>.
+Restart the container and open <http://127.0.0.1:3000/auto_source/>.
 When asked, enter your username and password.
 
 Then enter the URL of a website and click on the _Generate_ button.
@@ -152,8 +153,8 @@ If you're going to host a public instance, _please, please, please_:
 | `HEALTH_CHECK_PASSWORD`        | default: auto-generated on start   |
 |                                |                                    |
 | `AUTO_SOURCE_ENABLED`          | default: false                     |
-| `AUTO_SOURCE_USERNAME          | no default                         |
-| `AUTO_SOURCE_PASSWORD          | no default                         |
+| `AUTO_SOURCE_USERNAME`         | no default.                        |
+| `AUTO_SOURCE_PASSWORD`         | no default.                        |
 | `AUTO_SOURCE_ALLOWED_ORIGINS`  | no default.                        |
 |                                |                                    |
 | `PORT`                         | default: 3000                      |