Example names violate DNS naming stadards

Original names which gave errors:    myServiceA, myServiceB
Alatere suggestions:    
myServiceA --> myservicea, my_service_a, my-service-a
myServiceB --> myserviceb, my_service_b, my-service-b

docs/user-guide/basic-usage.md

@@ -8,35 +8,35 @@ First of all follow the instructions to install ingress-nginx. Then imagine that
 apiVersion: networking.k8s.io/v1beta1
 kind: Ingress
 metadata:
-  name: ingress-myServiceA
+  name: ingress-myservicea
   annotations:
     # use the shared ingress-nginx
     kubernetes.io/ingress.class: "nginx"
 spec:
   rules:
-  - host: myServiceA.foo.org
+  - host: myservicea.foo.org
     http:
       paths:
       - path: /
         backend:
-          serviceName: myServiceA
+          serviceName: myservicea
           servicePort: 80
 ---
 apiVersion: networking.k8s.io/v1beta1
 kind: Ingress
 metadata:
-  name: ingress-myServiceB
+  name: ingress-myserviceb
   annotations:
     # use the shared ingress-nginx
     kubernetes.io/ingress.class: "nginx"
 spec:
   rules:
-  - host: myServiceB.foo.org
+  - host: myserviceb.foo.org
     http:
       paths:
       - path: /
         backend:
-          serviceName: myServiceB
+          serviceName: myserviceb
           servicePort: 80
 ```