Add changelog of version 1.2.2
Remove an argument for regexp for highlight
Define a function to get a face for highlighting command
Use `guide-key/get-highlight-face' instead of `guide-key/propertize-string-according-to-command'
Delete `guide-key/propertize-string-according-to-command'
Change the type and the default value of `guide-key/highlight-command-regexp'
Modify a procedure to add regexp along with its type
Modify the docstring of `guide-key/highlight-command-regexp'
Bump a version to 1.2.3
Modify a docstring
Merge branch 'multiple-highlight'

Implement the feature to highlight multiple keywords (ref. #14).
Close #14.