docs: clarify that --data-path-addr doesn't restrict access

[dvdksn]

- What I did

Added a paragraph that clarifies the scope of the --data-path-addr for docker swarm init.

Relates to moby/moby#47667

- How I did it

- How to verify it

- Description for the changelog

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

[dvdksn]

cc @corhere

[codecov-commenter]

Codecov Report

Merging #4997 (faf096b) into master (c23a404) will decrease coverage by 0.03%. The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4997      +/-   ##
==========================================
- Coverage   61.04%   61.02%   -0.03%     
==========================================
  Files         295      295              
  Lines       20648    20648              
==========================================
- Hits        12605    12600       -5     
- Misses       7147     7150       +3     
- Partials      896      898       +2     

[thaJeztah]

Wondering if we should borrow some wording from --advertise-addr. Effectively (if my interpretation is correct here), --data-path-addr is advertising the address to use (I guess in hindsight, the flag should've been named to reflect that?)

https://github.com/docker/cli/blob/c23a40469888290e912035026bf53dffd32df360/docs/reference/commandline/swarm_init.md?plain=1#L95-L109