doc,comment: modified README and document comments (#28)

Author: sttk

README.md

@@ -120,7 +120,7 @@ If you want to prioritize the output of short option name first in the help text
 This crate provides the validator `cliargs::validators::validate_number<T>` which validates whether an option argument is valid format as a number.
 
 The ownership of the vector of option configurations which is passed as an argument of this method
-is moved to this method and set to the public field `cfgs` of [Cmd] instance.
+is moved to this method and set to the public field `cfgs` of `Cmd` instance.
 If you want to access the option configurations after parsing, get them from this field.
 
 ```
@@ -166,7 +166,7 @@ This method divides command line arguments to command arguments and options, the
 each option value to a curresponding field of the option store.
 
 Within this method, a vector of `OptCfg` is made from the fields of the option store.
-This [OptCfg] vector is set to the public field `cfgs` of the `Cmd` instance.
+This `OptCfg` vector is set to the public field `cfgs` of the `Cmd` instance.
 If you want to access this option configurations, get them from this field.
 
 An option configuration corresponding to each field of an option store is determined by

src/lib.rs

@@ -184,6 +184,42 @@
 //!     Err(err) => panic!("Invalid option: {}", err.option()),
 //! }
 //! ```
+//!
+//! ## Parse for a OptStore struct
+//!
+//! The [Cmd] struct has the method parse_for which parses command line arguments and set their option values to
+//! the option store which is passed as an argument.
+//!
+//! This method divides command line arguments to command arguments and options, then sets each option value to a
+//! curresponding field of the option store.
+//!
+//! Within this method, a vector of [OptCfg] is made from the fields of the option store. This [OptCfg] vector is
+//! set to the public field cfgs of the [Cmd] instance. If you want to access this option configurations, get them
+//! from this field.
+//! An option configuration corresponding to each field of an option store is determined by its type and opt field
+//! attribute.
+//! If the type is bool, the option takes no argument. If the type is integer, floating point number or string, the
+//! option can takes single option argument, therefore it can appear once in command line arguments.
+//! If the type is a vector, the option can takes multiple option arguments, therefore it can appear multiple times
+//! in command line arguments.
+//!
+//! A `opt` field attribute can have the following pairs of name and value: one is `cfg` to specify `names` and
+//! `defaults` fields of [OptCfg] struct, another is `desc` to specify `desc` field, and yet another is `arg` to
+//! specify `arg_in_help` field.
+//!
+//! The format of `cfg` is like `cfg="f,foo=123"`. The left side of the equal sign is the option name(s), and the
+//! right side is the default value(s).
+//! If there is no equal sign, it is determined that only the option name is specified.
+//! If you want to specify multiple option names, separate them with commas.
+//! If you want to specify multiple default values, separate them with commas and round them with square brackets,
+//! like `[1,2,3]`.
+//! If you want to use your favorite carachter as a separator, you can use it by putting it on the left side of the
+//! open square bracket, like `/[1/2/3]`.
+//!
+//! NOTE: A default value of empty string array option in a field attribute is `[]`, like `#[opt(cfg="=[]")]`, but
+//! it doesn't represent an array which contains only one empty string.
+//! If you want to specify an array which contains only one emtpy string, write nothing after `=` symbol, like
+//! `#[opt(cfg="=")]`.
 
 /// Enums for errors that can occur when parsing command line arguments.
 pub mod errors;