docs(slides): fix links for slides (#15015)
docs(slides): fix links for slides (#15015)

Links were pointing to https://beta.ionicframework.com/docs/api/Slides (upper-case 'S') when they should be pointing to "https://beta.ionicframework.com/docs/api/slides" (lower-case 's').
driftyco/ionic,driftyco/ionic,driftyco/ionic,driftyco/ionic,driftyco/ionic