Add CRL example from RFC 5280. Useful to verify GitHub issue #93.

examples/crl-rfc5280.b64

···
+CRL example from RFC5280 as found here:
+https://csrc.nist.gov/projects/pki-testing/sample-certificates-and-crls
+
+begin-base64 644 crl-rfc5280.der
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+BBgwFoAUCGivhTPIOUp6+IKTjnBqSiCELDIwCgYDVR0UBAMCAQwwDQYJKoZIhvcNAQEFBQADgYEA
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+r8FVF6IzTNYGmCuk/C4=
+====

index.html

···
             <option value="pkcs1.pem">PKCS#1 RSA key (RFC 8017)</option>
             <option value="pkcs8-rsa.pem">PKCS#8 RSA key (RFC 5208)</option>
             <option value="pkcs10.pem">PKCS#10 certification request (RFC 2986)</option>
+            <option value="crl-rfc5280.b64">CRL example (RFC 5280)</option>
             <option value="cmpv2.b64">CMP PKI message (RFC 4210)</option>
           </select>
           <input id="butExample" type="button" value="load"><br>