Training page in the top nav (#19214)

* Create new page and add to top nav

Signed-off-by: Celeste Horgan <celeste@cncf.io>

* The basics

Signed-off-by: Celeste Horgan <celeste@cncf.io>

* A bit of inline css

Signed-off-by: Celeste Horgan <celeste@cncf.io>

* Fix CSS

Signed-off-by: Celeste Horgan <celeste@cncf.io>

* Fix link + Add to bottom row

Signed-off-by: Celeste Horgan <celeste@cncf.io>

* Address feedback in PR

* Address feedback from elsewhere

* Fix button alignment

* Add training partners

* Simplify css

* Apply suggestions from review

Co-Authored-By: Zach Corleissen <zacharysarah@users.noreply.github.com>

* Fix landscape + text block widths

Co-authored-by: Zach Corleissen <zacharysarah@users.noreply.github.com>

assets/sass/_tablet.sass

@@ -222,9 +222,8 @@ $feature-box-div-width: 45%
   footer
     nav
       text-align: center
-
       a
-        width: 30%
+        width: auto
         padding: 0 20px
 
     .social