doc: elevate diagnostic report to tier1

diagnostic report qualifies for all the criteria for
being in tier1. Classify it as such.

PR-URL: #32732
Refs: nodejs/diagnostics#369
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Matheus Marchini <mat@mmarchini.me>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/guides/diagnostic-tooling-support-tiers.md

@@ -95,7 +95,8 @@ The tools are currently assigned to Tiers as follows:
 
  | Tool Type | Tool/API Name             | Regular Testing in Node.js CI | Integrated with Node.js | Target Tier |
  |-----------|---------------------------|-------------------------------|-------------------------|-------------|
- |           |                           |                               |                         |             |
+ | FFDC | diagnostic report | Yes | Yes | 1 |
+ | | | | | |
 
 ## Tier 2