Add the signature to the type

src/vs/vscode.d.ts

@@ -2967,6 +2967,17 @@ declare module 'vscode' {
 		 */
 		appendPlaceholder(value: string | ((snippet: SnippetString) => any), number?: number): SnippetString;
 
+		/**
+		 * Builder-function that appends a choice (`${1|a,b,c}`) to
+		 * the [`value`](#SnippetString.value) of this snippet string.
+		 *
+		 * @param values The values for choices - the array of strings
+		 * @param number The number of this tabstop, defaults to an auto-increment
+		 * value starting at 1.
+		 * @return This snippet string.
+		 */
+		appendChoice(values: string[], number?: number): SnippetString;
+
 		/**
 		 * Builder-function that appends a variable (`${VAR}`) to
 		 * the [`value`](#SnippetString.value) of this snippet string.