fix new doc for diskful new kernel patch (#3381)

* diskful kernel patch

* enhanced based on comments

docs/source/guides/admin-guides/manage_clusters/common/deployment/use_kernel_patch.rst

@@ -0,0 +1,24 @@
+Use new kernel patch
+====================
+
+This procedure assumes there are kernel RPM in /tmp, we take the osimage **rhels7.3-ppc64le-install-compute** as an example.
+The RPM names below are only examples, substitute your specific level and architecture.
+
+* **[RHEL]**
+
+#. The RPM kernel package is usually named: kernel-<kernelver>.rpm. Append new kernel packages directory to osimage pkgdir ::
+
+        mkdir -p /install/kernels/<kernelver>
+        cp /tmp/kernel-*.rpm /install/kernels/<kernelver>
+        createrepo /install/kernels/<kernelver>/
+        chdef -t osimage rhels7.3-ppc64le-install-compute -p pkgdir=/install/kernels/<kernelver>
+
+#. Inject the drivers from the new kernel RPMs into the initrd ::
+
+        mkdef -t osdistroupdate kernelupdate dirpath=/install/kernels/<kernelver>/ 
+        chdef -t osimage rhels7.3-ppc64le-install-compute osupdatename=kernelupdate
+        chdef -t osimage rhels7.3-ppc64le-install-compute netdrivers=updateonly
+        genitrd rhels7.3-ppc64le-install-compute --ignorekernelchk
+        nodeset <CN> osimage=rhels7.3-ppc64le-install-compute --noupdateinitrd     
+
+#. Boot CN from net normallly.

docs/source/guides/admin-guides/manage_clusters/ppc64le/diskful/customize_image/index.rst

@@ -11,6 +11,7 @@ Optional means all the subitems in this page are not necessary to finish an OS d
    pre_post_script.rst
    syncfile.rst
    additional_pkg.rst
+   use_kernel_patch.rst
    cfg_network_adapter.rst
    
    

docs/source/guides/admin-guides/manage_clusters/ppc64le/diskful/customize_image/use_kernel_patch.rst

@@ -0,0 +1,2 @@
+.. include:: ../../../common/deployment/use_kernel_patch.rst
+