Docs: add authorization header for MCP server based on OAuth 2.1 (#8293)
### What problem does this PR solve?
Add documentation of authorization header for MCP server based on OAuth
2.1
### Type of change
- [x] Documentation Update
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Co-authored-by: writinwaters <93570324+writinwaters@users.noreply.github.com>
### What problem does this PR solve?
_Briefly describe what this PR aims to solve. Include background context
that will help reviewers understand the purpose of the PR._
### Type of change
- [x] Documentation Update
Yongteng Lei
writinwaters