Add Sip guidelines

# Basic guidelines for formatting a Gulp Sips Series article

## Article Structure
Title
Large Image (replaces 55 words)
Series Description as shown: This is part of our Gulp Sips series: bringing you easily-digestible bits of information on our advanced or unknown features.
Body (can be What?, How?, Why?)

Notes:
* No more than 200 words/2 minute read, including images. This is based on the Medium’s basic time calculations.
* Add a cmd + enter between each titled section
* To add code to Medium
* Block code: add ```before your code
* To add inline code, type your code, highlight it, then click ` (a single tick).

No file or entry point is named. First locate the repository's existing Gulp Sips or article-guidance content, then add the listed structure and Medium formatting rules and verify the resulting guidance covers each requirement.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.