slog-handler-guide/README.md: stub

Add a file that will ultimately contain a guide to writing slog handlers.

This CL just creates the file so we can make a shortlink to it.

Change-Id: Ic31e62c6d92a480ecb7ba03cf052ca375f5abb94
Reviewed-on: https://go-review.googlesource.com/c/example/+/509735
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Jonathan Amsterdam <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

Author: jba

slog-handler-guide/README.md

@@ -0,0 +1,3 @@
+# A Guide to Writing `slog` Handlers
+
+This file will contain a guide to writing a slog handler.