Docs: updated notes on apollo kernel installation how-to

docs/howto/how_to_install_apollo_kernel.md

-# Installing the Apollo Kernel
-## Helpful hints before you begin
-* The Apollo runtime environment in the vehicle requires the Apollo Kernel. You are strongly recommended to install the pre-built kernel.
-
-## Installing Apollo Kernel
-
-1.  Download the release packages from the release section on GitHub:
-https://github.com/ApolloAuto/apollo-kernel/releases
-2.  Install the kernel after having the release package downloaded:
-    * ```tar zxvf linux-4.4.32-apollo-1.5.0.tar.gz```
-    * ```cd install```
-    * ```sudo bash install_kernel.sh```
-3.  Reboot your system using the reboot command
-4.  After rebooting, build the ESD CAN driver source code. Resources to build the ESD CAN driver source code can be found here: [ESDCAN-README.md](https://github.com/ApolloAuto/apollo-kernel/blob/master/linux/ESDCAN-README.md)
+# How to Install Apollo Kernel
+
+## Before you begin
+
+The Apollo Kernel is **ONLY** required by Apollo runtime in the vehicle. If your
+sole purpose was developing and testing on the Apollo platform, or running
+simulator software (e.g., the LGSVL simulator), then you don't need to install
+Apollo kernel at all.
+
+## Installing the Apollo Kernel
+
+- Download (latest) Apollo-kernel release from
+  [Apollo-kernel Releases on GitHub](https://github.com/ApolloAuto/apollo-kernel/releases)
+
+- Run the following commands to install the kernel after having the release
+  package downloaded:
+
+```bash
+tar zxvf linux-4.4.32-apollo-1.5.5.tar.gz
+cd install
+sudo bash install_kernel.sh
+```
+
+- Reboot your system
+
+- After rebooting, build the ESD CAN driver source code following the
+  [ESDCAN-README.md](https://github.com/ApolloAuto/apollo-kernel/blob/master/linux/ESDCAN-README.md)
+  guide.