docs: Point to main branch documentation on Swift Package Index

Author: euanh

README.md

@@ -1,6 +1,6 @@
 # Swift Container Plugin
 
-[![](https://img.shields.io/badge/docc-read_documentation-blue)](https://swiftpackageindex.com/apple/swift-container-plugin/documentation/swift-container-plugin)
+[![](https://img.shields.io/badge/docc-read_documentation-blue)](https://swiftpackageindex.com/apple/swift-container-plugin/main/documentation/swift-container-plugin)
 [![](https://img.shields.io/github/v/release/apple/swift-container-plugin?include_prereleases)](https://github.com/apple/swift-container-plugin/releases)
 [![](https://img.shields.io/endpoint?url=https%3A%2F%2Fswiftpackageindex.com%2Fapi%2Fpackages%2Fapple%2Fswift-container-plugin%2Fbadge%3Ftype%3Dswift-versions)](https://swiftpackageindex.com/apple/swift-container-plugin)
 [![](https://img.shields.io/endpoint?url=https%3A%2F%2Fswiftpackageindex.com%2Fapi%2Fpackages%2Fapple%2Fswift-container-plugin%2Fbadge%3Ftype%3Dplatforms)](https://swiftpackageindex.com/apple/swift-container-plugin)
@@ -69,6 +69,6 @@ Trying to pull registry.example.com/myservice@sha256:a3f75d0932d052dd9d448a1c904
 
 ## Getting Started
 
-Learn more about setting up your project in the [plugin documentation](https://swiftpackageindex.com/apple/swift-container-plugin/documentation/swift-container-plugin).
+Learn more about setting up your project in the [plugin documentation](https://swiftpackageindex.com/apple/swift-container-plugin/main/documentation/swift-container-plugin).
 
 Take a look at the [Examples](Examples).