docs(config): describes the priority of the configuration files

Author: shipengqi

README.md

@@ -98,7 +98,15 @@ $ make && ./_output/$(GOOS)/$(GOARCH)/bin/commitizen init
 
 ## Configuration
 
-You can set configuration file that `.czrc` at repository root, home directory, or the $XDG_CONFIG_HOME/commitizen directory. The configuration file that located in repository root have a priority over the one in home directory. The format is the same as the following:
+You can set configuration file that `.czrc` at repository root, home directory, or the `$XDG_CONFIG_HOME/commitizen` directory. 
+
+commitizen uses the following precedence order. Each item takes precedence over the item below it:
+
+- per-project config file (`/path/to/my/project/.czrc`)
+- per-user config file (`~/.czrc`)
+- `$XDG_CONFIG_HOME` config file (`$XDG_CONFIG_HOME/commitizen/.czrc`)
+
+The format is the same as the following:
 
 ```yaml
 name: default
@@ -394,4 +402,4 @@ items:
 format: "{{.type}}{{with .scope}}({{.}}){{end}}: {{.subject}}{{with .body}}\n\n{{.}}{{end}}{{with .footer}}\n\n{{.}}{{end}}"`
 ```
 
-![multiple-templates](https://github.com/shipengqi/illustrations/blob/e0d588dd70551344f0394cbf6671b15ae22e7635/commitizen/multiple-templates.png?raw=true)
+![multiple-templates](https://github.com/shipengqi/illustrations/blob/e0d588dd70551344f0394cbf6671b15ae22e7635/commitizen/multiple-templates.png?raw=true)