feat: add tutorial of enum

Author: MikhailMasny

package.json

@@ -4,7 +4,8 @@
   "description": "TypeScript Tutorials for GitHub",
   "main": "index.js",
   "scripts": {
-    "build": "tsc index.ts"
+    "build": "tsc index.ts",
+    "start": "node index.js"
   },
   "repository": {
     "type": "git",

typescript/enum.ts

@@ -0,0 +1,20 @@
+enum SomeEnum {
+    Prop1,
+    Prop2,
+    Prop3
+}
+
+const enumMember = SomeEnum.Prop1;
+const enumMemberReverse = SomeEnum[0];
+console.log(enumMember);
+console.log(enumMemberReverse);
+
+
+// Example of enum.
+enum MyEnum {
+    Prop1 = "Hello",
+    Prop2 = "World",
+    Prop3 = "!"
+}
+
+console.log(MyEnum.Prop1 + " " + MyEnum.Prop2);