Improve README build and import instructions

Add a section on building the documentation in Xcode.
Also, cleaned up the import documentation into Xcode section.

Author: stwrt

README.md

@@ -12,14 +12,24 @@ This will bring up a local web server, so you can view the documentation locally
 make preview
 ```
 
-### Docc Archive (Xcode)
+### DocC Archive (Xcode)
 
 Generate a DocC Archive that will be automatically imported into Xcode's documentation.
 
 ```
 make docc
 ```
 
+#### Build DocC Archive in Xcode
+
+Generate a DocC Archive in Xcode. This documentation will be available under the Workspace Documentation section.
+You will need to export `WebKit` and import it to add the DocC Archive to the Imported Documentation section.
+
+```
+Open Package.swift
+Product -> Build Documentation (⌃⇧⌘D)
+```
+
 ### GitHub Release
 
 Generate documentation for a release on GitHub Pages.
@@ -30,5 +40,5 @@ make github
 
 ## Import Documentation into Xcode
 
-Open `WebKit.doccarchive` and it will be automatically be imported into Xcode.
-Running `make docc` will also launch Xcode and import the document.
+Open `WebKit.doccarchive` and the documentation will be automatically imported into Xcode under the Imported Documention section.
+When running `make docc` the documentation will automatically be imported into Xcode.