x230: update microcode revision to 20 in docs

We have to do this for the release, see #34

x230/NEWS

@@ -3,6 +3,8 @@ skulls-x230 0.0.8 - tbd
 ---------------------------------------
 This release includes the following changes:
 * update SeaBIOS to version 1.11.2
+* update Intel's microcode revision from 1f to 20
+  (this includes Spectre Variant 3a and 4 mitigations)
 
 
 skulls-x230 0.0.7 - released 2018-06-18

x230/README.md

@@ -6,7 +6,7 @@
 * This directory's `./build.sh` should produce the exact release image file (from a skulls git checkout).
 Get it from our [release page](https://github.com/merge/coreboot-x230/releases)
 * __coreboot__: We take coreboot's master branch at the time we build a release image.
-* __microcode update__: revision `1f` from 2018-02-07 see package [20180312](https://downloadcenter.intel.com/download/27591) under [Intel's license](LICENSE.microcode)
+* __microcode update__: revision `20` from 2018-04-10
 * __SeaBIOS__: version [1.11.2](https://seabios.org/Releases) from 2018-06-02
 * The only proprietary binary, the VGA BIOS is executed in "secure" mode ([PCI_OPTION_ROM_RUN_YABEL](https://www.coreboot.org/Coreboot_Options))