feat(ror/form_basics): link to docs, explain HTTP method and CSRF relation

[XAJX179]

Because

#31019 (comment)

This PR

• changes the url_path name of an example in forms basic lesson.
• adds a paragraph about http methods and csrf not being checked on non GET requests and links to rails docs
• replaces a w3school link with mdn docs.

Issue

Closes #31019

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