markdownlint: disable line length via config

We don't want the markdownlint warning for line length when in a table
or code block but even with those disabled, markdownlint sometimes
gives spurious warnings.  Disable it with a config rather than as an
argument.

We will end up getting the code reformatted with prettier anyhow which
will handle line lengths on its own.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I6a6d2b2c798266ef067ba2b6b1e02279b59e1461
diff --git a/config/markdownlint.yaml b/config/markdownlint.yaml
index 15c9e81..dae3799 100644
--- a/config/markdownlint.yaml
+++ b/config/markdownlint.yaml
@@ -1,3 +1,4 @@
 default: true
+MD013: false
 MD024:
     siblings_only: true