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 <halcanary@google.com>
Reviewed-by: Hal Canary <halcanary@google.com>
diff --git a/docs/examples/Region_017.cpp b/docs/examples/Region_017.cpp
index a9f8317..ac27b42 100644
--- a/docs/examples/Region_017.cpp
+++ b/docs/examples/Region_017.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=985ff654a6b67288d322c748132a088e
-REG_FIDDLE(Region_017, 256, 256, true, 0) {
+REG_FIDDLE(Region_destructor, 256, 256, true, 0) {
 void draw(SkCanvas* canvas) {
     SkRegion* region = new SkRegion({1, 2, 3, 4});
     SkRegion region2(*region);