doc: format with markdownlint

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Id1efc27791e219e5fbfe08023143be2f59037307
diff --git a/.markdownlint.yaml b/.markdownlint.yaml
new file mode 100644
index 0000000..f5cfbee
--- /dev/null
+++ b/.markdownlint.yaml
@@ -0,0 +1,5 @@
+default: true
+MD024:
+    siblings_only: true
+MD013:
+    stern: true