added brief description of get and post method of form line 26-51

[katze-a0]

Because

The purpose of this PR is that I have added detailed description of GET and POST form methods in basic html css form section.

This PR

changes

1. GET and POST method explained
2. Basic code prototype for each method for better understanding.

Issue

this issue is related to issue #28796

Additional Information

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
• The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• If this PR addresses an open issue, it is linked in the Issue section
• If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• If any lesson files are included in this PR, they follow the Layout Style Guide
  

[MaoShizhong]

Thanks for the PR. We intend for this bit on GET and POST to just be a brief high level description of what they are, as opposed to a deeper example of exactly how they work/what request headers might look like. Those things are explored in more detail in each pathway's backend courses. So the current proposal is out of this lesson's scope.