[analysis_server] [lsp] Add docs for inlay hints config to readme

See #60326

Change-Id: I8d7faf4a48e3e3738cd97fba3f695e404318cab5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/441141
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Samuel Rawlins <[email protected]>
Reviewed-by: Samuel Rawlins <[email protected]>
Auto-Submit: Danny Tuppeny <[email protected]>

Author: DanTup

pkg/analysis_server/tool/lsp_spec/README.md

@@ -44,6 +44,15 @@ Client workspace settings are requested with `workspace/configuration` during in
 - `dart.updateImportsOnRename` (`bool?`): Whether to update imports and other directives when files are renamed. When unspecified, imports will be updated if the client supports `willRenameFiles` requests.
 - `dart.documentation` (`none`, `summary`, `full`): The kind of dartdocs to include in requests that can return large numbers of results such as Code Completion. If not set, defaults to `full`.
 - `dart.includeDependenciesInWorkspaceSymbols` (`bool?`): Whether to include symbols from dependencies and Dart/Flutter SDKs in Workspace Symbol results. If not set, defaults to `true`.
+- `dart.inlayHints` (`bool?` | `Object?`): Whether to show Inlay Hints. When set to `true`, enables all inlay hints with default settings. When set to `false`, disables all inlay hints. Can also be an object to configure individual hint types as defined below. Defaults to `true`.
+  - `parameterNames` (`{ "enabled": true | false | "none" | "literal" | "all" }`): Controls parameter name hints.
+    - `"none"` or `false`: show no parameter name hints
+	- `"literal"`: show hints only for arguments with literal values
+	- `"all"` or `true`: show hints for all parameters
+  - `parameterTypes` (`{ "enabled": bool }`): Whether to show Inlay Hints for inferred parameter types.
+  - `returnTypes` (`{ "enabled": bool }`): Whether to show Inlay Hints for inferred return types.
+  - `typeArguments` (`{ "enabled": bool }`): Whether to show Inlay Hints for inferred type arguments.
+  - `variableTypes` (`{ "enabled": bool }`): Whether to show Inlay Hints for inferred variable declarations.
 
 ## Method Status