Update docs

Author: yuanchuan

README.md

@@ -10,99 +10,103 @@ The css-doodle command line tool for previewing and generating images.
 npm install -g @css-doodle/cli
 ```
 
-## Commands
+After installation, you can use the `css-doodle` or `cssd` command in the terminal.
 
-### render
-Generate an image from the CSS Doodle source file.
+## Usage
 
-```bash
-cssd render code.css
 ```
+Usage: cssd [options] [command]
 
-#### -o, --output
-
-Custom output filename of the generated image.
+Options:
+  -V, --version  output the version number
+  -h, --help     display help for command
 
-```bash
-cssd render code.css -o result.png
+Commands:
+  render         Generate an image from css-doodle file
+  preview        Open a window to preview the css-doodle file
+  generate       Generate code using css-doodle generators
+  config         Display/set the configurations
+  use            Shorthand to fetch and use a custom version of css-doodle
+  parse          Print the parsed tokens, helped to debug on development
 ```
 
-#### -x, --scale
+## Commands
 
-Scale factor of the generated image, defaults to 1.
+### render
+Generate an image from the css-doodle source file. It'll read from STDIN if no source file specified.
 
+* `-o, --output`: Custom output filename of the generated image.
+* `-x, --scale`: Scale factor of the generated image, defaults to 1.
+ 
 ```bash
+cssd render
+cssd render code.css
+cssd render code.css -o result.png
 cssd render code.css -x 4
 ```
 
 ### preview
-Open a window to preview the CSS Doodle file.
-
-```bash
-cssd preview code.css
-```
-
-#### --fullscreen
+Open a window to preview the css-doodle file.
 
-Open the preview in fullscreen mode.
+* `--fullscreen`: Open in fullscreen mode.
 
 ```bash
+cssd preview code.css
 cssd preview code.css --fullscreen
 ```
 
+### generate
 
-### config
+Generate code using css-doodle generators.
 
-Display/set the configuration.
+* `svg`: Generate SVG code using svg() function.
+* `polygon`: Generate CSS polygon() using shape() function.
 
 ```bash
-cssd config
-```
-
-#### browserPath
-
-Use a custom browser to preview and generate images.
+cssd generate svg code.css
+cssd generate polygon code.css
 
-```bash
-cssd config browserPath /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome
+# read from STDIN
+cssd generate polygon
 ```
 
-### generate
+### config
 
-Generate code using CSS Doodle generators.
+Display/set the configurations in key/value pairs. Currently only two configuration names are recognized:
 
-#### svg
+* `set`:  Set a configuration with key/value pair.
+* `get`:  Get a configuration value by key.
+* `list`: List all configurations.
 
-Generate SVG code using svg() function.
+Recognizable configurations:
 
-```bash
-cssd generate svg code.css
-```
+* `browserPath`: The path to the browser executable.  
+* `css-doodle`: The path to the css-doodle to use.
 
-#### polygon
+```bash
+# show all configurations
+cssd config list
 
-Generate CSS polygon() using shape() function.
+# use a custom browser
+cssd config set browserPath /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome
 
-```bash
-cssd generate polygon code.css
-```
+# reset
+cssd config reset browserPath ''
 
-## Usage
+# get the value
+cssd config get browserPath
 
+# set the version of css-doodle
+cssd config set css-doodle 0.40.6
 ```
-Usage: css-doodle [options] [command]
 
-The css-doodle CLI for previewing and generating images
+### use
+Shorthand of `cssd config set css-doodle <version>`. 
 
-Options:
-  -V, --version               output the version number
-  -h, --help                  display help for command
+```bash
+cssd use css-doodle@0.40.6
 
-Commands:
-  render [options] [source]   generate an image from the CSS Doodle source file
-  preview [options] <source>  open a window to preview the CSS Doodle file
-  parse [source]              print the parsed tokens, helped to debug on development
-  config                      display/set the configuration
-  generate                    generate code using CSS Doodle generators
-  help [command]              display help for command
+# or just version
+cssd use 0.40.6
+cssd use latest
 ```