Reapply "format-code: fail on markdownlint warnings"

This reverts commit 6100d0bf6a0a30818a9508e344ea257df2574be6.

The reported issues were caused, not by markdownlint, but by a
upgrade of prettier that was not refreshed in all CI containers.

Change-Id: Ie5ec1849b5ee61cbfc5d376dfc14bf7a0aa1b89a
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/scripts/format-code.sh b/scripts/format-code.sh
index 5598f13..f49a027 100755
--- a/scripts/format-code.sh
+++ b/scripts/format-code.sh
@@ -255,9 +255,7 @@
 LINTER_IGNORE+=([markdownlint]=".markdownlint-ignore")
 LINTER_TYPES+=([markdownlint]="markdown")
 function do_markdownlint() {
-    markdownlint --config "${LINTER_CONFIG[markdownlint]}" -- "$@" || \
-        echo -e "    ${YELLOW}Failed markdownlint; temporarily ignoring."
-    # We disable line-length because prettier should handle prose wrap for us.
+    markdownlint --config "${LINTER_CONFIG[markdownlint]}" -- "$@"
 }
 
 LINTER_REQUIRE+=([meson]="meson;meson.build")