fix: terminology from "symbol link" to "symbolic link"

[CharlesCNorton]

Corrected the terminology from "symbol link" to "symbolic link" in the following instances for clarity and accuracy:

1. In the flags definition: Changed "Always follow symbol link in SRC_PATH" to "Always follow symbolic link in SRC_PATH"

2. In the client request comment: Changed "if client requests to follow symbol link, then must decide target file to be copied" to "if client requests to follow symbolic link, then must decide target file to be copied"

- What I did

Corrected the terminology from "symbol link" to "symbolic link" in two instances within the code.

- How I did it

Updated the flag description in the code and the corresponding comment to replace "symbol link" with "symbolic link" to ensure proper terminology is used.

- How to verify it

Review the changes in the relevant files to confirm that "symbol link" has been replaced with "symbolic link". Additionally, ensure that the functionality related to symbolic links operates as expected.

- Description for the changelog

Corrected terminology from "symbol link" to "symbolic link" in flag descriptions and comments.

- A picture of a cute animal (not mandatory but encouraged)

[thaJeztah]

/
Thank you for contributing! It appears your commit message is missing a DCO sign-off,
causing the DCO check to fail.

We require all commit messages to have a Signed-off-by line with your name
and e-mail (see "Sign your work"
in the CONTRIBUTING.md in this repository), which looks something like:

Signed-off-by: YourFirsName YourLastName <yourname@example.org>

There is no need to open a new pull request, but to fix this (and make CI pass),
you need to amend the commit(s) in this pull request, and "force push" the amended
commit.

Unfortunately, it's not possible to do so through GitHub's web UI, so this needs
to be done through the git commandline.

You can find some instructions in the output of the DCO check (which can be found
in the "checks" tab on this pull request), as well as in the Moby contributing guide.

Steps to do so "roughly" come down to:

1. Set your name and e-mail in git's configuration:

   git config --global user.name "YourFirstName YourLastName"
   git config --global user.email "yourname@example.org"

   (Make sure to use your real name (not your GitHub username/handle) and e-mail)

2. Clone your fork locally

3. Check out the branch associated with this pull request

4. Sign-off and amend the existing commit(s)

   git commit --amend --no-edit --signoff

   If your pull request contains multiple commits, either squash the commits (if
   needed) or sign-off each individual commit.

5. Force push your branch to GitHub (using the --force or --force-with-lease flags) to update the pull request.

Sorry for the hassle (I wish GitHub would make this a bit easier to do), and let me know if you need help or more detailed instructions!

[thaJeztah]

included in #6980