docs: update readme add motivation and more samples

README.md

@@ -1,6 +1,16 @@
 # Every
 
-Generate at rounded intervals for `Process.send_after/3`.
+Generate at even intervals for `Process.send_after/3`.
+Sometimes we need to have periodic tasks to execute exactly at
+certain intervals, for example run task every 15 minutes within hour
+so we want to execute our task
+
+1. At the beginning of hour,
+2. 15th minute,
+3. 30th minute,
+4. 45th minute.
+
+So instead of doing it manually it is better if it automated.
 
 ## Usage
 
@@ -20,6 +30,22 @@ then makes all calculation relative to given `DateTime` struct.
 optional parameter `relative_to` if provided then makes all calculation relative to
 given `DateTime` struct. First argument is literally to be read as `Every N minutes/hours`.
 
+All methods return duration in seconds so it is your task to turn secons into milleseconds etc.
+
+### How to use with periodic tasks
+
+```ex
+# Lets say we want to trigger our task every 5 minutes and current time is 12:02
+# so next call will be at 12:05, 12:10 ... 12:55 ...
+Process.send_after(self(), :work, Every.minutes(5) * 1000)
+
+# If we want to trigger every minute
+Process.send_after(self(), :work, Every.minute() * 1000)
+
+# If we want to trigger every hour
+Process.send_after(self(), :work, Every.hour() * 1000)
+```
+
 ## Installation
 
 If [available in Hex](https://hex.pm/docs/publish), the package can be installed