Rename swift.md for consistency with _lang.md pattern (#10599)

All other language-specific guide files are named `foo_lang.md`, as
distinct from `bazel.md` which is not for an implementation language
(and should probably get its own suffix, maybe bazel_build.md, but
that's another matter).

Signed-off-by: Clarence "Sparr" Risher <clrnc@amazon.com>

docs/getting-started/new-project-guide/swift_lang.md

@@ -4,7 +4,7 @@ title: Integrating a Swift project
 parent: Setting up a new project
 grand_parent: Getting started
 nav_order: 1
-permalink: /getting-started/new-project-guide/swift/
+permalink: /getting-started/new-project-guide/swift-lang/
 ---
 
 # Integrating a Swift project

docs/getting-started/new_project_guide.md

@@ -100,7 +100,7 @@ Programming language the project is written in. Values you can specify include:
 * [`rust`]({{ site.baseurl }}//getting-started/new-project-guide/rust-lang/)
 * [`python`]({{ site.baseurl }}//getting-started/new-project-guide/python-lang/)
 * [`jvm` (Java, Kotlin, Scala and other JVM-based languages)]({{ site.baseurl }}//getting-started/new-project-guide/jvm-lang/)
-* [`swift`]({{ site.baseurl }}//getting-started/new-project-guide/swift/)
+* [`swift`]({{ site.baseurl }}//getting-started/new-project-guide/swift-lang/)
 
 ### primary_contact, auto_ccs {#primary}
 The primary contact and list of other contacts to be CCed. Each person listed gets access to ClusterFuzz, including crash reports and fuzzer statistics, and are auto-cced on new bugs filed in the OSS-Fuzz