Update the library documentation

src/lib.rs

@@ -105,17 +105,25 @@
 //! The crate has an ability to inject environment variables into the configuration file. That
 //! becomes possible using special syntax: 
 //!
-//! * $"SOME_ENV_VAR_NAME"::bool for `ScalarValue::Boolean` 
-//! * $"SOME_ENV_VAR_NAME"::str for `ScalarValue::Str` 
-//! * $"SOME_ENV_VAR_NAME"::i32 for `ScalarValue::Integer32` 
-//! * $"SOME_ENV_VAR_NAME"::i64 for `ScalarValue::Integer64` 
-//! * $"SOME_ENV_VAR_NAME"::f32 for `ScalarValue::Floating32` 
-//! * $"SOME_ENV_VAR_NAME"::f64 for `ScalarValue::Floating64` 
+//! * `$"SOME_ENV_VAR_NAME"::str` to inject the environment variables `SOME_ENV_VAR_NAME` as the string value.
+//! No additiocal changes are made ot the value.
+//! * `$"SOME_ENV_VAR_NAME"::bool` to inject the environment variables `SOME_ENV_VAR_NAME` as the boolean value.
+//! The value `true` or `yes` or `on` or `1` are converted into `true` otherwise into `false`. 
+//! * `$"SOME_ENV_VAR_NAME"::int` to inject the environment variables `SOME_ENV_VAR_NAME` as the integer value.
+//! The successfully parsed value is injected as `i32` or `i64`, depending on the format, otherwise `0i32` is injected. 
+//! * `$"SOME_ENV_VAR_NAME"::flt` to inject the environment variables `SOME_ENV_VAR_NAME` as the floating value.
+//! The successfully parsed value is injected as `f32` or `f64`, depending on the format, otherwise `0f32` is injected. 
 //!
 //!
 //! **Example**:
 //!
 //! ```ignore
+//! #!/bin/sh
+//! export LOG_LEVEL=debug
+//! ```
+//! 
+//! ```ignore
+//! // Configuration file
 //! log = {
 //! // Inject (use) the value of the environment variable LOG_LEVEL
 //! level = $"LOG_LEVEL"::str;