New dir for UI cache management code

diff --git a/src/ui/cache/README b/src/ui/cache/README
new file mode 100644 (file)
index 0000000..1cdbaee
--- /dev/null
+++ b/src/ui/cache/README
@@ -0,0 +1,3 @@
+This directory is for utility code for maintaining caches of UI things,
+such as symbol previews, thumbnails, font lists, brushes, dashes, etc.
+