Update README.

Signed-off-by: Eric Wang <skygragon@gmail.com>

Author: skygragon

README.md

@@ -4,6 +4,7 @@
 * [company](/docs/company.md)
 * [cpp.lint](/docs/cpp.lint.md)
 * [cpp.run](/docs/cpp.run.md)
+* [github](/docs/github.md)
 * [lintcode](/docs/lintcode.md)
 * [solution.discuss](/docs/solution.discuss.md)
 
@@ -13,6 +14,12 @@ You can install the plugins in either ways below:
 
 ### Quick Install
 
-    $ leetcode plugin -i <plugin file>
+    $ leetcode plugin -i <plugin js file>
 
-To manage the installed plugins, please check [leetcode-cli's user guide](https://skygragon.github.io/leetcode-cli/commands#plugin).
+To manage the installed plugins, please check [leetcode-cli's user guide](https://skygragon.github.io/leetcode-cli/commands#plugin).
+
+### Configuration
+
+Some plugins could be configured with your customized options.
+
+Check [leetcode-cli's configuration](https://skygragon.github.io/leetcode-cli/advanced#configuration) for more details.