Make note about multiple instances

index.js

@@ -7,6 +7,8 @@ const createSyntaxUnhideStream = require("./src/phase-streams/syntax-unhide");
 const createKahnSortingStream = require("./src/phase-streams/sort-kahn");
 const createDedupeBundleCssStream = require("./src/phase-streams/dedupe-bundle-css");
 
+// FIXME: When there's >1 icssify instance set up on the Browserify instance (can this happen when a module specifies its own dependency on icssify?), either throw an error (if incompatible?) or merge the two somehow, so that there's only one resulting .css file
+
 function setupPipeline(browserify, options) {
 	/* Not shown here: the default 'deps' phase stream will process all the CSS files through our custom transform (defined elsewhere). That transform handles the discovery of CSS dependencies, by pre-processing the CSS files (normalizing 'composes' statements etc. into :import/:export statements), and then extracting all the imports from them, emitting them to Browserify as additional dependencies to fetch. */