typo: missing word: "to" (microsoft#27079)

Change:
...a resolve callback used resolve the promise...
to: 
...a resolve callback used to resolve the promise...

This PR suggested from: microsoft#27075

Author: bhamail

src/lib/es2015.promise.d.ts

@@ -7,7 +7,7 @@ interface PromiseConstructor {
     /**
      * Creates a new Promise.
      * @param executor A callback used to initialize the promise. This callback is passed two arguments:
-     * a resolve callback used resolve the promise with a value or the result of another promise,
+     * a resolve callback used to resolve the promise with a value or the result of another promise,
      * and a reject callback used to reject the promise with a provided reason or error.
      */
     new <T>(executor: (resolve: (value?: T | PromiseLike<T>) => void, reject: (reason?: any) => void) => void): Promise<T>;
@@ -193,4 +193,4 @@ interface PromiseConstructor {
     resolve(): Promise<void>;
 }
 
-declare var Promise: PromiseConstructor;
+declare var Promise: PromiseConstructor;