Add warning about async usage of provideTerminalLinks

Fixes #101458

src/vs/vscode.proposed.d.ts

@@ -1052,7 +1052,9 @@ declare module 'vscode' {
 
 	export interface TerminalLinkProvider<T extends TerminalLink = TerminalLink> {
 		/**
-		 * Provide terminal links for the given context.
+		 * Provide terminal links for the given context. Note that this can be called multiple times
+		 * even before previous calls resolve, make sure to not share global objects (eg. `RegExp`)
+		 * that could have problems when asynchronous usage may overlap.
 		 * @param context Information about what links are being provided for.
 		 */
 		provideTerminalLinks(context: TerminalLinkContext): ProviderResult<T[]>