readme: add note about oldMain()

README.md

@@ -18,6 +18,11 @@ over bmp files.
 # assumes lilv headers are at /usr/include/lilv-0, check build.zig if different
 git clone https://gitdab.com/luna/scritcher.git
 cd scritcher
+
+# edit src/main.zig so that oldMain points to main, and current main to oldMain
+# i'm working on the language part of scritcher and its right now separate from
+# the whole "porting lv2apply to zig" function.
+
 zig build install --prefix ~/.local/
 
 # on your input image file