vc: use git add -u to avoid accidentally staging untracked files

dotfiles/.bashrc

@@ -88,7 +88,7 @@ fi
 #export GCC_COLORS='error=01;31:warning=01;35:note=01;36:caret=01;32:locus=01:quote=01'
 
 vc() {
-    git add .
+    git add -u
     git commit -m "commit: $(date "+%Y-%m-%d %H:%M:%S")"
     git push
 }