doc: improve HACKING.md (canonical#484)

# Description

Add some missing dependencies for running unit test and static checks
locally.

## Type of change

Please delete options that are not relevant.

- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] CleanCode (Code refactor, test updates, does not introduce
functional changes)
- [x] Documentation update (Doc only change)

## How Has This Been Tested?

Created a LXD VM and install the following dependencies, and make sure
`make check-unit` and `make check-static` can run without issues.
```bash
sudo apt update
sudo apt install gcc make shellcheck 
sudo add-apt-repository ppa:dqlite/dev 
sudo apt install libdqlite-dev
sudo snap install go --classic
export PATH=$PATH:$HOME/go/bin

git clone https://github.com/canonical/microceph.git
cd microceph/microceph
make
```

## Contributor's Checklist

Please check that you have:

- [x] self-reviewed the code in this PR.
- [ ] added code comments, particularly in hard-to-understand areas.
- [ ] updated the user documentation with corresponding changes.
- [ ] added tests to verify effectiveness of this change.

Signed-off-by: Chi Wai Chan <[email protected]>

HACKING.md

@@ -65,15 +65,15 @@ Building MicroCeph is as easy as a snap!
 # v for verbose output of the build process.
 snapcraft -v
 ...
-Creating snap package 
-...                                                                                                                                                                     
+Creating snap package
+...
 Created snap package microceph_0+git.ac1da26_amd64.snap
-``` 
+```
 
 The newly created .snap artifact can then be installed as
 ```bash
 # Dangerous flag for locally built snap
-sudo snap install --dangerous microceph_*.snap 
+sudo snap install --dangerous microceph_*.snap
 ```
 
 ```bash
@@ -85,12 +85,29 @@ sudo snap restart microceph.daemon
 ```
 
 ## 👍 Unit-Testing
-The MicroCeph [makefile](/microceph/Makefile) has targets for running unit tests and lint checks. They can be run as follows.
+The MicroCeph [Makefile](/microceph/Makefile) has targets for running unit tests and lint checks. However, you will need the following packages or tool to run them locally.
+
 ```bash
-# Note: commands executed from microceph subdir which contains the Makefile.
+# Add general requirements
+sudo apt install gcc make shellcheck
+
+# Add libdqlite-dev, required for building microceph
+sudo add-apt-repository ppa:dqlite/dev -y
+sudo apt install -y libdqlite-dev
+
+# Install go and export the binary to PATH
+sudo snap install go --classic
+export PATH=$PATH:$HOME/go/bin
+```
+
+Once you install the prerequisite, you can run unit tests and lint checks as follows:
+
+```bash
+cd microceph
+
 # Run unit tests
 make check-unit
 
 # Run static checks
 make check-static
-```
+```