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/extend/plugins_network.md

@@ -1,13 +1,8 @@
-<!--[metadata]>
-+++
-title = "Docker network driver plugins"
-description = "Network driver plugins."
-keywords = ["Examples, Usage, plugins, docker, documentation, user guide"]
-[menu.main]
-parent = "engine_extend"
-weight=5
-+++
-<![end-metadata]-->
+---
+title: "Docker network driver plugins"
+description: "Network driver plugins."
+keywords: ["Examples, Usage, plugins, docker, documentation, user guide"]
+---
 
 # Engine network driver plugins