util/util_readme: update to give additional information

Add a note to the top of the util.md document saying not to edit it.

The Documentation/util.md file had been updated to contain additional
information at the bottom.  This copies that information into the file
after it's been created.

Change-Id: I4b08439420ceb706df62e3949406585ea34c1514
Signed-off-by: Martin Roth <gaumless@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64580
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
diff --git a/util/util_readme/post_util.md b/util/util_readme/post_util.md
new file mode 100644
index 0000000..9533cb1
--- /dev/null
+++ b/util/util_readme/post_util.md
@@ -0,0 +1,16 @@
+## In depth documentation
+
+* [cbfstool](util/cbfstool/index.md)
+* [ifdtool](util/ifdtool/index.md)
+* [intelp2m](util/intelp2m/index.md)
+
+## Generated documentation
+
+**Please do not edit the markdown file in the documentation directory
+*directly.**
+
+This file was generated by running util_readme.sh. Please make sure it
+is rerun when new tools are added or when documentation is updated.
+
+To update, edit the markdown files in the util directory, then
+re-generate this file by running `util/util_readme/util_readme.sh`
diff --git a/util/util_readme/util_readme.sh b/util/util_readme/util_readme.sh
index af688c4..986c393 100755
--- a/util/util_readme/util_readme.sh
+++ b/util/util_readme/util_readme.sh
@@ -10,13 +10,25 @@
 UTIL_DIR=$(dirname "$UTIL_README_DIR")
 COREBOOT_ROOT_DIR=$(dirname "$UTIL_DIR")
 DOCMENTATION_DIR="$COREBOOT_ROOT_DIR/Documentation"
-SUMMARY="_Scripts and programs found in the \`./util\` directory_"
+SUMMARY='
+## List of utils
+
+_Scripts and programs found in the coreboot `./util` directory_
+'
+APPEND_TO_UTIL_MD="${UTIL_README_DIR}/post_util.md"
 
 DESCRIPTION_FILES=$(find "$UTIL_DIR" -name "description.md" | sort)
 
 echo -n "" > "$UTIL_DIR/README.md"
-echo "# Utilities" > "$DOCMENTATION_DIR/util.md"
-echo "$SUMMARY" >> "$DOCMENTATION_DIR/util.md"
+{
+  echo
+  echo "[//]: # ( DO NOT EDIT - AUTOGENERATED FILE )";
+  echo
+  echo "[//]: # ( RUN 'util/util_readme/util_readme.sh' to regenerate )";
+  echo;
+  echo "# Utilities";
+  echo "${SUMMARY}"
+} > "${DOCMENTATION_DIR}/util.md"
 
 for DESC_FILE in $DESCRIPTION_FILES; do
   UTIL_NAME=$(echo "$DESC_FILE" | rev | cut -d '/' -f2 | rev)
@@ -40,3 +52,5 @@
   echo "$DESC" >> "$UTIL_DIR/README.md"
   echo "$DESC" >> "$DOCMENTATION_DIR/util.md"
 done
+
+cat "${APPEND_TO_UTIL_MD}" >> "${DOCMENTATION_DIR}/util.md"