chore: Modified .git-attributes excluding files from git-archive

git-archive is used on github to provide release-packages

Author: hoppfrosch

.gitattributes

@@ -3,8 +3,9 @@
 .gitattributes export-ignore
 .gitignore export-ignore
 .gitmodules export-ignore
-# test directory
 t export-ignore
 _build export-ignore
 src export-ignore
-.vscode export-ignore
+.vscode export-ignore
+.code-workspace export-ignore
+lib/readme.txt export-ignore