chore: tweak comments

Author: yyx990803

lib/loader.js

@@ -91,7 +91,14 @@ module.exports = function (content) {
     output += 'var disposed = false\n'
   }
 
-  // add requires for styles
+  // resolve <style> blocks into a `injectStyle` function
+  // - normal mode: injectStyle contains requires to modules that directly
+  //                inject styles on import
+  // - server mode: injectStyle contains required modules with injectors
+  //                (exposed as __inject__ by vue-style-loader) so that they
+  //                can be called with ssrContext
+  // - shadow mode: injectStyle contains required modules with injectors and
+  //                injects to root component's shadowRoot.
   let cssModules
   if (parts.styles.length) {
     const needsExplicitInjection = isServer || isShadowMode
@@ -209,7 +216,7 @@ module.exports = function (content) {
     output += 'var __vue_template__ = null\n'
   }
 
-  // template functional
+  // <template functional>
   output += '/* template functional */\n'
   output +=
     'var __vue_template_functional__ = ' +