Add an example demonstrating SNI usage.
diff --git a/examples/sni/example.invalid.key b/examples/sni/example.invalid.key
new file mode 100644
index 0000000..192e346
--- /dev/null
+++ b/examples/sni/example.invalid.key
@@ -0,0 +1,15 @@
+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----