Add README info on how to create custom builds. Close gh-892.

README.md

@@ -45,7 +45,7 @@ First, clone a copy of the main jQuery git repo by running:
git clone git://github.com/jquery/jquery.git
```

Enter the directory and install the node dependencies:
Enter the directory and install the Node dependencies:

```bash
cd jquery && npm install
@@ -81,6 +81,18 @@ Starting in jQuery 1.8, special builds can now be created that optionally exclud
- offset


Before creating a custom build for use in production, be sure to check out the latest stable version:

```bash
git pull; git checkout $(git describe --abbrev=0 --tags)
```

Then, make sure all Node dependencies are installed and all Git submodules are checked out:

```bash
npm install && grunt
```

To create a custom build, use the following special `grunt` commands:

Exclude **ajax**: