docs(overlay): fix typos in flex position comments (#11241)

Author: willshowell

src/cdk/overlay/position/flexible-connected-position-strategy.ts

@@ -310,7 +310,7 @@ export class FlexibleConnectedPositionStrategy implements PositionStrategy {
   }
 
   /**
-   * Adds a new preferred fallback position.
+   * Adds new preferred positions.
    * @param positions List of positions options for this overlay.
    */
   withPositions(positions: ConnectedPosition[]): this {
@@ -328,7 +328,7 @@ export class FlexibleConnectedPositionStrategy implements PositionStrategy {
   }
 
   /**
-   * Sets a minimum distance the ovelray may be positioned to the edge of the viewport.
+   * Sets a minimum distance the overlay may be positioned to the edge of the viewport.
    * @param margin Required margin between the overlay and the viewport edge in pixels.
    */
   withViewportMargin(margin: number): this {