add AndoniMartin as a contributor for content

[allcontributors]

Adds @AndoniMartin as a contributor for content.

This was requested by sspencerwire in this comment

[skip ci]

[github-actions]

Test results for c79a925:

Number of broken URLs: 7

URL,RESULT,FILENAME
 https://www.clusterlabs.org/,failed,books/web_services/07-high-availability.md
 https://cisecurity.org,failed,books/disa_stig/disa_stig_part2.md
 http://your_ip,failed,guides/cms/mediawiki.md
 http://$(hostname):8080,failed,guides/repositories/pulp_fetch_upload.md
 https://ftp.gnu.org/gnu/tar/,failed,guides/backup/tar.md
 https://ftp.gnu.org/gnu/hello/hello-2.12.tar.gz,failed,labs/systems_administration_I/lab7-software_management.md
 https://repocompare.rockylinux.org,failed,release_notes/8_5.md