Fix example intros

[gewarren]

No description provided.

[Copilot]

Pull request overview

This PR simplifies and standardizes the example documentation for the EventAttribute class. The changes focus on cleaning up redundant section headers and consolidating code snippets.

• Removes redundant "Remarks" and "Examples" headings from markdown documentation
• Consolidates multiple code snippets into single Snippet5 blocks
• Updates EventSource references from xref format to markdown links
• Adjusts snippet markers in code files to match the consolidated structure

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

File	Description
xml/System.Diagnostics.Tracing/EventAttribute.xml	Cleaned up documentation structure by removing redundant headings, consolidating code snippet references, and updating EventSource cross-references to markdown links
snippets/visualbasic/System.Diagnostics.Tracing/EventAttribute/Overview/program.vb	Updated snippet markers to consolidate Snippet5-8 into a single Snippet5 block
snippets/csharp/System.Diagnostics.Tracing/EventAttribute/Overview/program.cs	Updated snippet markers to consolidate Snippet5-8 into a single Snippet5 block

[BillWagner]

This LGTM @gewarren

Did you check that the snippets this PR no longer references are still needed? If not, let's remove them.