util/amdtools/README,description.md: add update_efs_spi_speed docs

This change is mostly from CB:56644 patchset 3.

Signed-off-by: Martin Roth <martin@coreboot.org>
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Idece950bab260a099c9790485805cbe8ea641666
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61895
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
diff --git a/util/amdtools/README.md b/util/amdtools/README.md
index c628f55..0e48d89 100644
--- a/util/amdtools/README.md
+++ b/util/amdtools/README.md
@@ -1,6 +1,10 @@
 # amdtools
 Various tools for AMD platforms
 
+## A tool to update the SPI speed set in the EFS table
+This works for Stoney Ridge and Zen class AMD processors.
+ - update_efs_spi_speed
+
 ## A set of tools to compare (extended) K8 memory settings.
  - k8-compare-pci-space.pl
  - k8-interpret-extended-memory-settings.pl
diff --git a/util/amdtools/description.md b/util/amdtools/description.md
index 9c075eb..fc9f1c5 100644
--- a/util/amdtools/description.md
+++ b/util/amdtools/description.md
@@ -1,4 +1,5 @@
 Various tools for AMD processors
+* update_efs_spi_speed - Change SPI speed in binary. `Bash`
 * A set of tools to compare extended K8 memory settings. `Perl`
   * k8-compare-pci-space.pl - Shows differences between values
     in PCI space and the default value. `Perl`