Add prettier RC file

This file is copied from openbmc-build-scripts:config/prettierrc.yaml,
which is the default for BMC CI. The presence of the RC file is so that
autoformat plugins/extensions will now if this project should be
formatted.

Change-Id: I31430dd26d7c2ddd2d46fa125e164d31b157982b
Signed-off-by: Zane Shelley <zshelle@us.ibm.com>
diff --git a/.prettierrc.yaml b/.prettierrc.yaml
new file mode 100644
index 0000000..a69b879
--- /dev/null
+++ b/.prettierrc.yaml
@@ -0,0 +1,7 @@
+tabWidth: 4
+printWidth: 80
+proseWrap: "always"
+overrides:
+    - files: "*.md"
+      options:
+          tabWidth: 2