nix*: add Spanish translations

[4jamesccraven]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page(s) have at most 8 examples.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known):

[tldr-bot]

The build for this PR failed with the following error(s):

pages.es/common/nix-build.2.md:7: TLDR005 Example descriptions should end in a colon with no trailing characters
pages.es/common/nix-repl.md:7: TLDR005 Example descriptions should end in a colon with no trailing characters

Please fix the error(s) and push again.

[4jamesccraven]

I did my best to follow the conventions that others use for particular word choices, but I'm open to constructive criticism if something could be improved. Also, I think I fixed the issue with the link, but if not let me know and I will fix it.

Thanks!

[4jamesccraven]

@kant Sorry, I wouldn't have done them all individually if I realised how many there were... I just wanted to accept your changes. If I need to do something to squash the commits let me know. I hope I didn't cause any inconvenience.

[kant]

@4jamesccraven Relax!