DOCC_EXEC in swift package manager: typos and cleanup

Author: natikgadzhi

README.md

@@ -151,13 +151,10 @@ You can also test a locally built version of Swift-DocC using Swift Package Mana
 CLI. SwiftPM will try to read `DOCC_EXEC` environment variable value, and use
 the path you provded if it's set.
 
-  1. In your test `Package.swift`, add a dependency on `swift-docc-plugin`.
-     [`swift-docc-plugin`](https://github.com/apple-swift-docc-plugin) is a 
-     Swift Package Manager plugin that invokes `docc` for you, see details in 
-     `swift-docc-plugin`.
+  1. In your test `Package.swift`, add a dependency on [`Swift-DocC Plugin`](https://github.com/apple/swift-docc-plugin).
   2. Set `DOCC_EXEC` environment variable and run documentation generation
      command like this:
-     
+
         `DOCC_EXEC=/path/to/docc swift package generate-documentation`
 
 ## Using `docc` to build and preview documentation