Docs: Give documentation examples better names

These names come from the bookmaker generated md files.

Also, delete ducplicated and empty examples.

A later CL will re-name the cpp files.

Change-Id: Ie365b9cc1cc705d010c674b9988b32c8307a0455
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/201609
Commit-Queue: Hal Canary <[email protected]>
Reviewed-by: Hal Canary <[email protected]>
diff --git a/docs/examples/Canvas_125.cpp b/docs/examples/Canvas_125.cpp
index 509e849..33ce86e 100644
--- a/docs/examples/Canvas_125.cpp
+++ b/docs/examples/Canvas_125.cpp
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
 #include "fiddle/examples.h"
 // HASH=c093c2b14bd3e6171ede7cd4049d9b57
-REG_FIDDLE(Canvas_125, 256, 256, false, 3) {
+REG_FIDDLE(Canvas_drawAtlas_4, 256, 256, false, 3) {
 void draw(SkCanvas* canvas) {
   // sk_sp<SkImage> image = mandrill;
   SkRSXform xforms[] = { { 1, 0, 0, 0 }, {0, 1, 300, 100 } };