Added comments

internal/arduino/builder/libraries.go

@@ -161,11 +161,17 @@ func (b *Builder) compileLibrary(library *libraries.Library, includes []string)
 		b.logger.Info(i18n.Tr(`Compiling library "%[1]s"`, library.Name))
 	}
 
+	/* TODO: if a single library needs a rebuild then all libraries requires a rebuild.
+	   This means that the `canUseArchivedLib` must be checked for all libraries
+	   in advance in the `compileLibraries` method.
+	*/
+
 	var targetArchivedLibrary *paths.Path
 	if b.librariesBuildCachePath != nil {
 		archivedLibName := getCachedLibraryArchiveDirName(
 			b.buildProperties.Get("build.fqbn"),
 			b.buildProperties.Get("compiler.optimization_flags"),
+			/* TODO: Add included library set here */
 			library.InstallDir,
 		)