Extract example from the README to a runnable location.

examples/jack.vcf

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+BEGIN:VCARD
+VERSION:3.0
+UID: 5db6f100-e2d6-4e8d-951f-d920586bc069
+N:Foster;Jack;Allen;;
+FN:Allen Foster
+REV:20230408T122102Z
+EMAIL;TYPE=home;TYPE=pref:allen@fosters.test
+EMAIL;TYPE=work:jack.foster@company.test
+TEL;TYPE=CELL:+1 (555) 123-4567
+END:VCARD

examples/simple.nim

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+import vcard
+
+# Reading in an existing vcard
+let vcards = parseVCard3File("jack.vcf")
+assert vcards.len == 1
+let vcAllen = vcards[0]
+
+assert vcAllen.email.len == 2
+assert vcAllen.email[0].value == "allen@fosters.test"
+assert vcAllen.n.given[0] == "Jack"
+
+# Creating a new VCard
+var vcSusan: VCard3
+vcSusan.add(@[
+  newVC3_N(given = @["Susan"], family = @["Foster"]),
+  newVC3_Email(value = "susan@fosters.test", emailType = @["PREF",
+  $etInternet]),
+  newVC3_Tel(
+    value = "+1 (555) 444-3889",
+    telType = @[$ttHome, $ttCell, $ttVoice, $ttMsg])
+])
+writeFile("susan.vcf", $vcSusan)