updated docs; added parsed ROM images to .gitignore

.gitignore

@@ -2,3 +2,5 @@ apple2e.rom
 disk.rom
 *~
 *.o
+apple/applemmu-rom.h
+apple/diskii-rom.h

README.md

@@ -19,6 +19,26 @@ Build log:
 
   https://hackaday.io/project/19925-aiie-an-embedded-apple-e-emulator
 
+Getting the ROMs
+================
+
+As with many emulators, you have to go get the ROMs yourself. I've got
+the ROMs that I dumped out of my Apple //e. You can probably get yours
+a lot easier.
+
+There are two files that you'll need:
+
+  apple2e.rom  -- a 32k dump of the entire Apple //e ROM
+  disk.rom     -- a 256 byte dump of the DiskII controller ROM (16-sector P5)
+
+The MD5 sums of those two files are:
+
+  003a780b461c96ae3e72861ed0f4d3d9 apple2e.rom
+  2020aa1413ff77fe29353f3ee72dc295 disk.rom
+
+From those, the appropriate headers will be automatically generated by
+"make roms" (or any other target that relies on the ROMs).
+
 Building (on a Mac)
 ===================