docs: Update how to add project via SPM #675

Job	Run time
linux	2m 16s
test (platform=iOS\ Simulator,OS=17.5,name=iPhone\ 15\ Pro\ Max, test)	6m 4s
windows	2m 23s
spm-test	4m 50s
test (platform\=tvOS\ Simulator,OS=17.5,name\=Apple\ TV, test)	5m 43s
test (platform=watchOS\ Simulator,name=Apple\ Watch\ Series\ 9\ \(41mm\), build)	1m 17s
test (platform=macOS, test)	6m 19s
test (platform=visionOS\ Simulator,OS=1.2,name=Apple\ Vision\ Pro, build)	1m 41s
cocoapods	8m 14s
xcode-test-5_5	1m 15s
docs	1m 24s
	41m 26s

Provide feedback