Add Swift package index

Author: kimdv

.spi.yml

@@ -0,0 +1,11 @@
+# This is manifest file for the Swift Package Index for it to
+# auto-generate and host DocC documentation.
+# For reference see https://swiftpackageindex.com/swiftpackageindex/spimanifest/documentation/spimanifest/commonusecases#Host-DocC-documentation-in-the-Swift-Package-Index.
+
+version: 1
+builder:
+  configs:
+    - documentation_targets:
+        # First item in the list is the "landing" (default) target
+        - SwiftFormat
+      custom_documentation_parameters: [--experimental-skip-synthesized-symbols]