Clarify

The note regarding dragging FMDB files to Swift project was confusing, so I have attempted to clarify.

Thanks to peakman https://github.com/ccgus/fmdb/pull/438 for raising this topic

README.markdown

@@ -267,7 +267,11 @@ You can use FMDB in Swift projects too.
 
 To do this, you must:
 
-1. Copy the FMDB `.m` and `.h` files into your project.
+1. Copy the relevant `.m` and `.h` files from the FMDB `src` folder into your project.
+
+ You can copy all of them (which is easiest), or only the ones you need. Likely you will need [`FMDatabase`](http://ccgus.github.io/fmdb/html/Classes/FMDatabase.html) and [`FMResultSet`](http://ccgus.github.io/fmdb/html/Classes/FMResultSet.html) at a minimum. [`FMDatabaseAdditions`](http://ccgus.github.io/fmdb/html/Categories/FMDatabase+FMDatabaseAdditions.html) provides some very useful convenience methods, so you will likely want that, too. If you are doing multithreaded access to a database, [`FMDatabaseQueue`](http://ccgus.github.io/fmdb/html/Classes/FMDatabaseQueue.html) is quite useful, too.
+
+ Note, if you're copying all of the files to your project, you may want to drag the individual files into your project, not the folder, itself, because if you drag the folder, you won't be prompted to add the bridging header (see next point).
 
 2. If prompted to create a "bridging header", you should do so. If not prompted and if you don't already have a bridging header, add one.