Convert Markdown frontmatter to YAML

Some frontmatter such as the weights, menu stuff, etc is no longer used
'draft=true' becomes 'published: false'

Signed-off-by: Misty Stanley-Jones <misty@docker.com>
Upstream-commit: b30609446d212624e3d4ce814c70130b75c552a0
Component: engine

components/engine/docs/reference/commandline/attach.md

@@ -1,12 +1,8 @@
-<!--[metadata]>
-+++
-title = "attach"
-description = "The attach command description and usage"
-keywords = ["attach, running, container"]
-[menu.main]
-parent = "smn_cli"
-+++
-<![end-metadata]-->
+---
+title: "attach"
+description: "The attach command description and usage"
+keywords: ["attach, running, container"]
+---
 
 # attach