Docs: Add instructions for how to configure `git` to use an ssh key without `ssh-agent`
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- [x] Start this issue's title with `Docs:` or `Docs feedback:`.
## Problem to solve
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Doc Section Affected: (User/SSH/Generate An SSH Key Pair)[https://docs.gitlab.com/user/ssh/#generate-an-ssh-key-pair]
In the codebase: https://gitlab.com/gitlab-org/gitlab/-/blob/master/doc/user/ssh.md#generate-an-ssh-key-pair
The process that's not addressed sufficiently:
If a user wants to use git with an ssh key, but does not have the admin privileges to run `ssh-agent`.
Currently, the docs do not address the above process and assumes the user is able to run `ssh-agent`, which may not always be the case.
## Further details
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Usecase: Users do not have admin privileges on their operating system, but still want to serve/use their ssh key with git.
References: `git config` option [`core.sshCommand`](https://git-scm.com/docs/git-config#Documentation/git-config.txt-coresshCommand)
## Proposal
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Add a section in docs for how users can configure git to use `core.sshCommand` if they do not have the privileges to run `ssh-agent`.
Something like so:
```
### Configure Git to use an SSH key without administrative privileges
If you do not have sufficient privileges to run `ssh-agent`, you may not be able to serve your SSH key such
that git recognizes your SSH key. In such a case, you can still configure git to use a particular SSH key.
This can be done with the `git config` option
[`core.sshCommand`](https://git-scm.com/docs/git-config#Documentation/git-config.txt-coresshCommand),
like so: `git config --global core.sshCommand "ssh -i <path/to/ssh_private_key>"`.
E.g.
```bash
git config --global core.sshCommand = "ssh -i ~/.ssh/id_ed25519"
```
```
## Who can address the issue
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No special expertise required
## Other links/references
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N/A
/label ~"documentation"
/label ~"docs-only"
/label ~"type::maintenance" ~"maintenance::refactor"
/milestone %Backlog
issue