Migrating plugins content

[nate-double-u]

First pass of migrating CNI Plugins documentation. fixes: #14

Deploy preview: https://deploy-preview-24--cni.netlify.app/

[nate-double-u]

Deploy preview: https://deploy-preview-24--cni.netlify.app/

Interesting pages in preview: https://deploy-preview-24--cni.netlify.app/plugins/ <- plugins index https://deploy-preview-24--cni.netlify.app/plugins/plugins/main/windows/win-bridge/ <- this is how the READMEs down the tree are exposed.

Any *.md file has been brought over, and anything named README.md has been renamed to _index.md in their project folder to serve the page. "Extra" emty _index.md files have had to be added to make the navigation work. for example: https://deploy-preview-24--cni.netlify.app/plugins/vendor/golang.org/x/sys/unix/ here, vendor/, golang.org/, x/, and sys/all have empty _index.md files in them.

Here is the structure from content/plugins (note, i'm not super happy with the duplication of plugins in the url structure here, but for now I'll leave it)

.
├── CONTRIBUTING.md
├── OWNERS.md
├── RELEASING.md
├── _index.md
├── pkg
│   ├── _index.md
│   └── ns
│       └── _index.md
├── plugins
│   ├── _index.md
│   ├── ipam
│   │   ├── _index.md
│   │   ├── dhcp
│   │   │   └── _index.md
│   │   ├── host-local
│   │   │   └── _index.md
│   │   └── static
│   │       └── _index.md
│   ├── main
│   │   ├── _index.md
│   │   ├── bridge
│   │   │   └── _index.md
│   │   ├── host-device
│   │   │   └── _index.md
│   │   ├── ipvlan
│   │   │   └── _index.md
│   │   ├── macvlan
│   │   │   └── _index.md
│   │   ├── ptp
│   │   │   └── _index.md
│   │   └── windows
│   │       ├── CONTRIBUTORS.md
│   │       ├── _index.md
│   │       ├── win-bridge
│   │       │   └── _index.md
│   │       └── win-overlay
│   │           └── _index.md
│   ├── meta
│   │   ├── _index.md
│   │   ├── bandwidth
│   │   │   └── _index.md
│   │   ├── firewall
│   │   │   └── _index.md
│   │   ├── flannel
│   │   │   └── _index.md
│   │   ├── portmap
│   │   │   └── _index.md
│   │   ├── sbr
│   │   │   └── _index.md
│   │   ├── tuning
│   │   │   └── _index.md
│   │   └── vrf
│   │       └── _index.md
│   └── sample
│       └── _index.md
└── vendor
    ├── _index.md
    ├── github.com
    │   ├── Microsoft
    │   │   ├── _index.md
    │   │   ├── go-winio
    │   │   │   └── _index.md
    │   │   └── hcsshim
    │   │       └── _index.md
    │   ├── _index.md
    │   ├── alexflint
    │   │   ├── _index.md
    │   │   └── go-filemutex
    │   │       └── _index.md
    │   ├── buger
    │   │   ├── _index.md
    │   │   └── jsonparser
    │   │       └── _index.md
    │   ├── d2g
    │   │   ├── _index.md
    │   │   ├── dhcp4
    │   │   │   └── _index.md
    │   │   ├── dhcp4client
    │   │   │   └── _index.md
    │   │   └── dhcp4server
    │   │       └── _index.md
    │   ├── godbus
    │   │   └── dbus
    │   │       └── CONTRIBUTING.md
    │   ├── j-keck
    │   │   ├── _index.md
    │   │   └── arping
    │   │       └── _index.md
    │   ├── mattn
    │   │   ├── _index.md
    │   │   └── go-shellwords
    │   │       └── _index.md
    │   ├── onsi
    │   │   ├── _index.md
    │   │   ├── ginkgo
    │   │   │   ├── CHANGELOG.md
    │   │   │   └── _index.md
    │   │   └── gomega
    │   │       ├── CHANGELOG.md
    │   │       └── _index.md
    │   ├── safchain
    │   │   ├── _index.md
    │   │   └── ethtool
    │   │       └── _index.md
    │   ├── sirupsen
    │   │   ├── _index.md
    │   │   └── logrus
    │   │       ├── CHANGELOG.md
    │   │       └── _index.md
    │   └── vishvananda
    │       ├── _index.md
    │       ├── netlink
    │       │   ├── CHANGELOG.md
    │       │   └── _index.md
    │       └── netns
    │           └── _index.md
    └── golang.org
        ├── _index.md
        └── x
            ├── _index.md
            └── sys
                ├── _index.md
                └── unix
                    └── _index.md

58 directories, 66 files

[nate-double-u]

inviting @zacharysarah for review.