Update links to point to tutorial page

The old link is broken and this seems like the proper one. Addresses p5.js-website#527

Author: muffinista

Diff for: src/accessibility/describe.js

@@ -28,7 +28,7 @@ const labelTableElId = '_lte_'; //Label Table Element
  * visible to screen readers. This is the default mode.
  *
  * Read
- * <a href="/learn/accessible-labels.html">Writing accessible canvas descriptions</a>
+ * <a href="/tutorials/writing-accessible-canvas-descriptions/">Writing accessible canvas descriptions</a>
  * to learn more about making sketches accessible.
  *
  * @method describe
@@ -179,7 +179,7 @@ p5.prototype.describe = function(text, display) {
  * mode.
  *
  * Read
- * <a href="/learn/accessible-labels.html">Writing accessible canvas descriptions</a>
+ * <a href="/tutorials/writing-accessible-canvas-descriptions/">Writing accessible canvas descriptions</a>
  * to learn more about making sketches accessible.
  *
  * @method describeElement

Diff for: src/accessibility/outputs.js

@@ -34,7 +34,7 @@ import p5 from '../core/main';
  * mode.
  *
  * Read
- * <a href="/learn/accessible-labels.html">Writing accessible canvas descriptions</a>
+ * <a href="/tutorials/writing-accessible-canvas-descriptions/">Writing accessible canvas descriptions</a>
  * to learn more about making sketches accessible.
  *
  * @method textOutput
@@ -169,7 +169,7 @@ p5.prototype.textOutput = function(display) {
  * mode.
  *
  * Read
- * <a href="/learn/accessible-labels.html">Writing accessible canvas descriptions</a>
+ * <a href="/tutorials/writing-accessible-canvas-descriptions/">Writing accessible canvas descriptions</a>
  * to learn more about making sketches accessible.
  *
  * @method gridOutput