docs: added a section for precompiled filetypes (#1440)

Author: mfranzke

packages/docs/src/docs/pattern-managing-assets.md

@@ -52,6 +52,12 @@ Pattern Lab has a configuration object which allows users to separate source pat
 
 Note how some sets of files even extend into the "vendor" `./node_modules/` directory. Relative paths are the default but absolute paths are supported also. You may also use these paths within the Grunt or Gulp taskfiles by referring to the `paths()` function.
 
+## Preprocessed files
+
+In case you're using a preprocessor to e.g. compile TypeScript files to JavaScript files, or SCSS/SASS files to CSS files, you might want to use your solution of choice, that perfectly fits your needs. Pattern lab doesn't restrict you at all on this, and as well doesn't deliver any defaults for the general pattern files. So e.g. you could install [`sass` node package](https://www.npmjs.com/package/sass) to compile `.scss` files, add a script to your `package.json` as well, and let those files get genereated at the `./source/css` folder.
+
+You might want to even also ignore those source files from being copied over to your `public` folders, as they won't need to get delivered to a hosting environment, which we describe in the next section.
+
 ## Preventing specific filetypes from being copied
 
 If you'd like to prevent specific filetypes from being copied from your `source` to your `public` folder like e.g. CSS preprocessor source files (`.scss`), you could specify those within an array of your pattern lab config: