Fix more minor typos

src/app/HealthCertificateBarcode.qml

@@ -56,7 +56,7 @@ QQC2.Page {
                     return i18n("Certificate invalid");
                 }
                 if (certificate.signatureState == KHC.HealthCertificate.UnknownSignature) {
-                    return i18n('Unknown issuer certficiate');
+                    return i18n('Unknown issuer certificate');
                 }
 
                 switch (certificate.type) {

src/app/android/res/values/strings.xml

@@ -8,5 +8,5 @@
     <string name="application_name_short">Itinerary</string>
 
     <string name="shortcut_label_current_ticket_short">Current Ticket</string>
-    <string name="shortcut_label_health_certs_short">Health Certficates</string>
+    <string name="shortcut_label_health_certs_short">Health Certificates</string>
 </resources>