Add more description how to install PGroonga on OS X

install/os-x.md

@@ -15,6 +15,26 @@ You can install PGroonga by Homebrew:
 % brew install postgresql --with-pgroonga
 ```
 
+If you want to use [MeCab](http://taku910.github.io/mecab/) based tokenizer, you need to reinstall `groonga` package with `--with-mecab` option:
+
+```text
+% brew reinstall groonga --with-mecab
+```
+
+Create a database:
+
+```text
+% psql --command 'CREATE DATABASE pgroonga_test'
+```
+
+(Normally, you should create a user for `pgroonga_test` database and use the user.)
+
+Connect to the created database and execute `CREATE EXTENSION pgroonga`:
+
+```text
+% psql -d pgroonga_test --command 'CREATE EXTENSION pgroonga'
+```
+
 That's all!
 
 Try [tutorial](../tutorial/). You can understand more about PGroonga.