build: correct Xcode spelling in .gitignore

PR-URL: #38895
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

.gitignore

@@ -117,7 +117,7 @@ tools/*/*.i.tmp
 /build
 /coverage
 
-# === Rules for XCode artifacts ===
+# === Rules for Xcode artifacts ===
 *.xcodeproj
 *.xcworkspace
 *.pbxproj