Improve top-level documentation

This patch introduced the changes:
- Build instructions
- Strip duplicated commands
- Add more hyperlinks
- Mention nerdctl as Docker CLI replacement

Author: jserv

README.md

@@ -1,16 +1,31 @@
 # The Linux Kernel Module Programming Guide
 
-This project keeps the Linux Kernel Module Programming Guide reasonably up to date, with [working examples](examples/) for recent 5.x kernel versions.
+This project keeps the Linux Kernel Module Programming Guide up to date, with [working examples](examples/) for recent 5.x kernel versions.
 The guide has been around since 2001 and most copies of it on the web only describe old 2.6.x kernels.
 
 The book can be freely accessed via https://sysprog21.github.io/lkmpg/ or [latest PDF file](https://github.com/sysprog21/lkmpg/releases).
 The original guide may be found at [Linux Documentation Project](http://www.tldp.org/LDP/lkmpg/).
 
 ## Getting Started
 
-### Compile on Local Machine
+### Summary
+1. Get the latest source code from the [GitHub page](https://github.com/sysprog21/lkmpg).
+2. Install the prerequisites.
+3. Generate PDF and/or HTML documents.
 
-To prepare for build this book on your local machine, we're going to install TeXLive (MacTeX). On various Unix/Linux operating systems, this can be done simply by:
+### Step 1: Get the latest source code
+
+Make sure you can run `git` with an Internet connection.
+
+```shell
+$ git clone https://github.com/sysprog21/lkmpg.git && cd lkmpg
+```
+
+### Step 2: Install the prerequisites
+
+To gernate the book from source, [TeXLive](https://www.tug.org/texlive/) ([MacTeX](https://www.tug.org/mactex/)) is required.
+
+For Ubuntu Linux, macOS, and other Unix-like systems, run the following command(s):
 
 ```bash
 # Debian / Ubuntu
@@ -24,35 +39,22 @@ $ brew install --cask mactex
 $ sudo tlmgr update --self
 ```
 
-Now we could build document with following commands:
-
-```bash
-# download project
-$ git clone https://github.com/sysprog21/lkmpg.git && cd lkmpg
+Alternatively, using [Docker](https://docs.docker.com/) is recommended, as it guarantees the same dependencies with our GitHub Actions wokrflow.
+After install [docker engine](https://docs.docker.com/engine/install/) on your machine, pull the docker image [twtug/lkmpg](https://hub.docker.com/r/twtug/lkmpg) and run in isolated containers.
 
-# run commands
-$ make all              # Generate PDFdocument
-$ make html             # Convert TeX to HTML
-$ make clean            # Delete generated files
+```shell
+# pull docker image and run it as container
+$ docker pull twtug/lkmpg
+$ docker run --rm -it -v $(pwd):/workdir twtug/lkmpg
 ```
 
-### Compile with Docker
-
-The compilation could be completed flawlessly using Docker. **Using Docker is recommended, as it guarantees the same dependencies with our GitHub Actions wokrflow.
+[nerdctl](https://github.com/containerd/nerdctl) is a Docker-compatible command line tool for [containerd](https://containerd.io/), and you can replace the above `docker` commands with `nerdctl` counterparts.
 
-After [install docker engine](https://docs.docker.com/engine/install/) on your machine, pulling the docker image [twtug/lkmpg](https://hub.docker.com/r/twtug/lkmpg) and compile with it.
+### Step 3: Generate PDF and/or HTML documents
 
-Execute followings
+Now we could build document with following commands:
 
 ```bash
-# download project
-$ git clone https://github.com/sysprog21/lkmpg.git && cd lkmpg
-
-# pull docker image and run it as container
-$ docker pull twtug/lkmpg
-$ docker run --rm -it -v $(pwd):/workdir twtug/lkmpg
-
-# run commands
 $ make all              # Generate PDF document
 $ make html             # Convert TeX to HTML
 $ make clean            # Delete generated files