docs: add github sponsorship

Author: lwouis

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: lwouis

alt-tab-macos.xcodeproj/project.pbxproj

@@ -234,6 +234,7 @@
 		BF0C898614108C8DC7A178BB /* el */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.strings; name = el; path = InfoPlist.strings; sourceTree = "<group>"; };
 		BF0C899605B39AB4EE0E8EB8 /* icon_512x512.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = icon_512x512.png; sourceTree = "<group>"; };
 		BF0C89A541FBEA23E7CB1D94 /* lb */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.strings; name = lb; path = Localizable.strings; sourceTree = "<group>"; };
+		BF0C89F6EA16DD7322626E20 /* FUNDING.yml */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.yaml; path = FUNDING.yml; sourceTree = "<group>"; };
 		BF0C8A50151A4EF88E494357 /* da */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.strings; name = da; path = InfoPlist.strings; sourceTree = "<group>"; };
 		BF0C8B15FFB262ECC54B5AA4 /* sl */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.strings; name = sl; path = InfoPlist.strings; sourceTree = "<group>"; };
 		BF0C8B2C057099EDABE46779 /* Button.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Button.swift; sourceTree = "<group>"; };
@@ -887,6 +888,7 @@
 			children = (
 				D04BAD7008ED1D9CBC147A75 /* pull_request_template.md */,
 				D04BA7A56A2009957C939159 /* ISSUE_TEMPLATE */,
+				BF0C89F6EA16DD7322626E20 /* FUNDING.yml */,
 			);
 			path = .github;
 			sourceTree = "<group>";