added isGeneric method and tests

README.md

@@ -1,2 +1,19 @@
 # email-checker
 Email checker is package with a collection of different methods of checking email addresses.
+
+```go
+package main
+
+import "github.com/lukerodham/email-checker"
+
+func main() {
+    is, err := checker.IsGeneric("example@gmail.com")
+    if err != nil {
+        panic(err)
+    }
+
+    if is {
+        // do something?
+    }
+}
+```