Update documentation

Author: Sija

README.md

@@ -46,6 +46,25 @@ foo = FooWithTimeSpan.from_yaml("span: 1 hour, 15 minutes")
 foo.ttl # => 01:15:00
 ```
 
+> [!TIP]
+> Allowed suffixes:
+>
+> - week: `w`, `week(s)`
+> - day: `d`, `day(s)`
+> - hour: `h`, `hour(s)`
+> - minute: `m`, `min`, `minute(s)`
+> - second: `s`, `sec`, `second(s)`
+> - nanosecond: `ns`, `nanosecond(s)`
+
+> [!TIP]
+> Valid string examples:
+>
+> - `1w2d3h4m5s`
+> - `1w 2d 3h 4m 5s`
+> - `1w 2d 3h 4 min 5 sec`
+> - `1 week 2 days 3 hours 4 minutes 5 seconds`
+> - `1 week, 2 days, 3 hours, 4 minutes, 5 seconds`
+
 ## Contributing
 
 1. Fork it (<https://github.com/Sija/tssc.cr/fork>)

src/core_ext/time/span.cr

@@ -1,3 +1,5 @@
+# A module for converting time span strings into `Time::Span` objects and
+# the other way around.
 module Time::Span::StringConverter
   private PATTERN = %r{
     (?:(?<sign>[+-])\s*)?