Add some explanation to readme

README.md

@@ -12,12 +12,73 @@ Still, just to be safe, I explicitly discourage using `bart` for mission-critica
 
 ## Installation
 
-### From source on Linux
+### From source
 
 ```
 $ make install
 ```
 
 ### Binaries
 
-You can get them from GitHub releases.
+You can get them from [GitHub releases](https://github.com/mp4096/bart/releases).
+
+
+## Usage example
+
+You want to send an HTML email stored as a [Mustache template](https://mustache.github.io/) in `template.mustache`.
+Your configuration (see below) is defined in `config.bart.yml`.
+
+To preview the rendered emails, call `bart` without the send `-s` flag:
+
+```
+$ bart -m template.mustache -c config.bart.yml
+Hello, Jane Doe
+Send flag not set: opening preview in "chromium-browser"
+Send flag not set: opening preview in "chromium-browser"
+```
+
+To send the email, add the send flag `-s`:
+
+```
+$ bart -m template.mustache -c config.bart.yml -s
+Hello, Jane Doe
+Please enter your credentials for "smtpserver.xyz.com"
+Login: janedoe
+Password:
+Will send to [[email protected] [email protected]]
+Will send to [[email protected] [email protected]]
+```
+
+Since this email will not appear in your provider's `Sent` folder,
+`bart` will send you a BCC copy.
+
+For help, call `bart -h`.
+
+## How to configure
+
+Here's an example config file:
+
+```yaml
+author:
+ name: Jane Doe
+ email: [email protected]
+ browser: chromium-browser
+
+email_server:
+ hostname: smtpserver.xyz.com
+ port: 123
+
+global_context:
+ subject: Global subject
+
+recipients:
+ [email protected]:
+ salutation: Hi John
+ subject: Local subject, overrides global one
+ [email protected]:
+ salutation: Hello Max
+```
+
+Basically, `recipients` is a hashmap keyed by recipient email addresses;
+the values are local contexts specific for each recipient.
+Notice that local context overrides global one!