Fixed the documentation targets for the Makefile file.

Makefile

@@ -19,6 +19,11 @@ environment ?= .env
 include $(environment)
 export $(shell sed 's/=.*//' $(environment))
 
+# Uses the DocC executable from Xcode's default toolchain, as some Swift toolchains (e.g. 6.4.0) ship an x86_64-only one.
+DOCC_EXEC ?= $(shell xcrun --toolchain com.apple.dt.toolchain.XcodeDefault --find docc 2>/dev/null)
+
+export DOCC_EXEC
+
 # LIBRARY
 
 lib-build: ## Builds the library