Simplify template-no-deprecated docs to be user-facing

Remove implementation detail from Rule Details; drop broken "see future
work" reference since that doc was removed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: wagenet

docs/rules/template-no-deprecated.md

@@ -8,7 +8,7 @@ This rule requires TypeScript (`parserServices.program` must be present). It is
 
 ## Rule Details
 
-The rule resolves template references through ESLint's scope analysis: a `<Component>` or `{{helper}}` reference is traced back to its import declaration, then the TypeScript type checker inspects the exported symbol's JSDoc tags for `@deprecated`.
+This rule checks if imported Glimmer components, helpers, or modifiers are marked `@deprecated` in their JSDoc.
 
 **Covered syntax:**
 
@@ -19,7 +19,7 @@ The rule resolves template references through ESLint's scope analysis: a `<Compo
 | Block component         | `{{#DeprecatedBlock}}…{{/DeprecatedBlock}}` |
 | Modifier                | `<div {{deprecatedModifier}}>`              |
 
-**Not covered (see future work):** `<MyComp @deprecatedArg={{x}}>` — argument names are not scope-registered by the parser.
+**Not covered:** `<MyComp @deprecatedArg={{x}}>` — argument names are not scope-registered by the parser.
 
 ## Examples