kubeadm: update the reference documentation for 1.15 (#14596)

* kubeadm-ref: update placeholder generated files

* kubeadm-ref: include reset-phase.md document

Also update reset.md to reflect the addition of reset phases.

* kubeadm-ref: update authored content

* kubeadm-ref: remove imports for removed "config upload" commands

* kubeadm-ref: add page for kubeadm upgrade phases

content/en/docs/reference/setup-tools/kubeadm/generated/kubeadm_version.md

@@ -3,7 +3,6 @@ Print the version of kubeadm
 
 ### Synopsis
 
-
 Print the version of kubeadm
 
 ```
@@ -12,50 +11,14 @@ kubeadm version [flags]
 
 ### Options
 
-<table style="width: 100%; table-layout: fixed;">
-  <colgroup>
-    <col span="1" style="width: 10px;" />
-    <col span="1" />
-  </colgroup>
-  <tbody>
-
-    <tr>
-      <td colspan="2">-h, --help</td>
-    </tr>
-    <tr>
-      <td></td><td style="line-height: 130%; word-wrap: break-word;">help for version</td>
-    </tr>
-
-    <tr>
-      <td colspan="2">-o, --output string</td>
-    </tr>
-    <tr>
-      <td></td><td style="line-height: 130%; word-wrap: break-word;">Output format; available options are 'yaml', 'json' and 'short'</td>
-    </tr>
-
-  </tbody>
-</table>
-
-
+```
+  -h, --help            help for version
+  -o, --output string   Output format; available options are 'yaml', 'json' and 'short'
+```
 
 ### Options inherited from parent commands
 
-<table style="width: 100%; table-layout: fixed;">
-  <colgroup>
-    <col span="1" style="width: 10px;" />
-    <col span="1" />
-  </colgroup>
-  <tbody>
-
-    <tr>
-      <td colspan="2">--rootfs string</td>
-    </tr>
-    <tr>
-      <td></td><td style="line-height: 130%; word-wrap: break-word;">[EXPERIMENTAL] The path to the 'real' host root filesystem.</td>
-    </tr>
-
-  </tbody>
-</table>
-
-
+```
+      --rootfs string   [EXPERIMENTAL] The path to the 'real' host root filesystem.
+```