Add init.d setup example

[gabrielfeo]

Suggest the possibility of applying injecting the Develocity init script for all builds by moving it to init.d.

Manually tested on a GitLab repository:

• .gitlab-ci.yml file containing the snippet (slightly different as it used mv instead of cp)
• Job proving script was applied

[alextu]

It should work but have you been able to test the documented snippet (manually) ?

[gabrielfeo]

@alextu, could you review again, please? I added a mkdir in case the Gradle user home doesn't exist yet and changed mv to cp so that the variable DEVELOCITY_INIT_SCRIPT_PATH keeps making sense.

It should work but have you been able to test the documented snippet (manually) ?

I had not, wanted to hear if it made sense to you first. I updated the description with links to a test.