Migs647/spm how to (#1002)

* Added SPM support in README.md

Author: migs647

README.md

@@ -69,6 +69,39 @@ Note: Segment _strongly_ recommends that you use a dynamic framework to manage y
 github "segmentio/analytics-ios"
 ```
 
+### Swift Package Manager (SPM)
+
+To add analytics-ios via Swift Package Mangaer, it is possible to add it one of two ways:
+
+#### Xcode
+![Xcode Add SPM Package](https://user-images.githubusercontent.com/917994/119199146-69765200-ba3f-11eb-9173-93cfb5f3cabd.png)
+
+![ChoosePackageRepository](https://user-images.githubusercontent.com/917994/119199143-68ddbb80-ba3f-11eb-9bf2-5dc11c208abd.png)
+
+![ChoosePackageOptions](https://user-images.githubusercontent.com/917994/119199139-67ac8e80-ba3f-11eb-9941-fc541030f3df.png)
+
+
+#### Package.swift
+```
+import PackageDescription
+
+let package = Package(
+    name: "MyApplication",
+    dependencies: [
+        // Add a package containing Analytics as the name along with the git url
+        .package(
+            name: "Segment",
+            url: "[email protected]:segmentio/analytics-ios.git"
+        )
+    ],
+    targets: [
+        name: "MyApplication",
+        dependencies: ["Segment"] // Add Analytics as a dependency of your application
+    ]
+)
+```
+Note: Segment recommends that you use Xcode to add your package.
+
 ## Quickstart
 
 Refer to the Quickstart documentation at [https://segment.com/docs/libraries/ios/quickstart](https://segment.com/docs/libraries/ios/quickstart/).