Installing Koji kernel. Booting specific kernel by default.

Added the following changes:

- quickdoc for installing kernel from Koji
- booting page and HowTo for booting a specific kernel by default

modules/ROOT/nav.adoc

@@ -71,10 +71,12 @@
 ** xref:upgrading-fedora-online.adoc[Upgrading Fedora using package manager]
 
 * xref:kernel/overview.adoc[Kernel and booting]
+** xref:kernel/booting.adoc[Booting]
 ** xref:kernel/troubleshooting.adoc[Troubleshooting]
 ** xref:kernel/build-custom-kernel.adoc[Building a Custom Kernel]
 ** xref:kernel/howto-kernel-testday.adoc[Guide for Kernel Test Days]
 ** xref:debug-dracut-problems.adoc[How to debug Dracut problems]
+** xref:kernel/installing-koji-kernel.adoc[Installing a kernel from Koji]
 
 * Virtualization
 ** xref:getting-started-with-virtualization.adoc[Getting started with virtualization (libvirt)]

modules/ROOT/pages/_partials/proc_booting-specific-kernel-default.adoc

@@ -0,0 +1,16 @@
+[[booting_specific_kernel_default]]
+== Setting an installed kernel to boot by default
+
+To set a specific installed kernel to boot by default, use the following command
+
+----
+sudo grubby --set-default /boot/vmlinuz-n.nn.nn-nnn.fcnn.x86_64
+----
+
+where `vmlinuz-n.nn.nn-nnn.fcnn` is the version of installed kernel as can be found in the `/boot` directory.
+
+[[sect-references]]
+=== References:
+
+* https://docs.fedoraproject.org/en-US/fedora/rawhide/system-administrators-guide/kernel-module-driver-configuration/Working_with_the_GRUB_2_Boot_Loader/[Fedora Rawhide Docs :: Working with the GRUB 2 Boot Loader]
+* https://docs.fedoraproject.org/en-US/Fedora/23/html/System_Administrators_Guide/sec-Configuring_GRUB_2_Using_the_grubby_Tool.html[Using the grubby tool]

modules/ROOT/pages/dnf.adoc

@@ -112,6 +112,7 @@ If you have used this configuration, you can disable it in individual DNF comman
 
 If you use a GUI update application which does not allow you to specify packages to exclude when they run, this method can be used.
 
+[[sect-using-dnf-plugin]]
 === Using the DNF Versionlock plugin
 
 You can also use the DNF `versionlock` plugin to limit the packages that are included in a transaction.

modules/ROOT/pages/kernel/booting.adoc

@@ -0,0 +1,4 @@
+Booting
+=======
+
+include::{partialsdir}/proc_booting-specific-kernel-default.adoc[]

modules/ROOT/pages/kernel/installing-koji-kernel.adoc

@@ -0,0 +1,45 @@
+= Installing kernel from Koji
+
+:description: A quick guide on installing a kernel from the Koji repository.
+
+Koji is the build system Fedora developers use to build software for inclusion into Fedora. If there is a need to install a kernel different from the one that gets installed by default, these can be obtained from the Koji repository.
+
+== Install the koji package
+
+The koji package makes this process much easier. Let's install the package:
+
+    $ sudo dnf install koji
+
+== Download and install the kernel
+
+Below is a one-line command that creates a new unique temporary directory, downloads kernel RPMs to it and installs them. This assumes we are working with the `x86_64` architecture.
+
+    cd $(mktemp -d) \
+      && koji download-build --arch=x86_64 --arch=noarch kernel-n.nn.nn-nnn.fcnn \
+      && sudo dnf install *
+
+This eliminates the need to clean up after installation and the risk of installing unwanted rpms accidentally.
+
+The following part of the above command downloads the kernel and its dependencies for the given architecture and kernel version.
+
+    koji download-build --arch=[arch] kernel-n.nn.nn-nnn.fcnn
+
+where [arch] indicates the architecture i.e. `x86_64`
+
+== Additional Steps:
+
+The following additional steps are often useful:
+
+* Set the default boot option - so this boots automatically subsequently
+
+See xref:kernel/booting.adoc[quick-doc on setting a specific kernel to boot by default]
+
+* Add a versionlock to ensure this version is not deleted when kernel updates are installed
+
+See xref:dnf.adoc#sect-using-dnf-plugin[quick-doc on using the dnf versionlock plugin]
+
+[[sect-references]]
+== References
+
+. https://fedoramagazine.org/install-kernel-koji/#comment-472889[Fedora Magazine article: How to install a kernel from koji]
+