Remove deprecated Boxed groups from docs

docs/content/components/boxed-groups.md

@@ -1,49 +0,0 @@
----
-title: Boxed groups (deprecated)
-path: components/boxed-group
-status: Deprecated
-source: 'https://github.com/github/github/blob/master/app/assets/stylesheets/components/boxed-groups.scss'
-symbols:
-  [
-    BtnGroup,
-    Counter,
-    ajax-error-message,
-    approved,
-    avatar,
-    bleed-flush,
-    boxed-action,
-    boxed-group,
-    boxed-group-action,
-    boxed-group-breadcrumb,
-    boxed-group-inner,
-    boxed-group-list,
-    boxed-group-standalone,
-    boxed-group-table,
-    boxed-group-warning,
-    btn-sm,
-    compact,
-    compact-options,
-    condensed,
-    dangerzone,
-    dashboard-sidebar,
-    field-with-errors,
-    flush,
-    heading,
-    help,
-    inline-error,
-    markdown-body,
-    octicon,
-    octicon-alert,
-    one-half,
-    rejected,
-    seamless,
-    selected,
-    spinner,
-    standalone,
-    tabnav,
-    tabnav-tab,
-    visible,
-  ]
----
-
-The `boxed-group` styles have been deprecated. Please use the [Box component](/components/box) instead.

docs/src/@primer/gatsby-theme-doctocat/nav.yml

@@ -75,8 +75,6 @@
       url: /components/box-overlay
     - title: Box
       url: /components/box
-    - title: Boxed groups (deprecated)
-      url: /components/boxed-groups
     - title: Branch name
       url: /components/branch-name
     - title: Breadcrumbs