Docs feedback: Fixing the documantation for git submodule usage: relative URL example

Problem to solve

Under the git sub-module documentation - git submodule usage: relative URL example

[submodule "project"]
  path = project
  url = ../../project.git

Further details

There's a need to change the documentation as the usage of git submodule with relative path is referring to the dir itself and not to the .git file

Proposal

Change the documentation to

[submodule "project"]
  path = project
  url = ../../project

Other links/references

doc/ci/git_submodules.md