pambrighten: add Spanish translation

[kant]

• 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 PR title conforms to the recommended templates.
• Version of the command being documented (if known):

[tricantivu]

Suggested change

	`pambrighten -value {{valor_porcentual}} {{ruta/a/imagen.pam}} > {{ruta/a/salida.pam}}`
	`pambrighten -value {{valor_porcentual}} {{ruta/a/imagen.pam}} > {{ruta/a/archivo_de_salida.pam}}`

[tricantivu]

Suggested change

	`pambrighten -saturation {{valor_porcentual}} {{ruta/a/imagen.pam}} > {{ruta/a/salida.pam}}`
	`pambrighten -saturation {{valor_porcentual}} {{ruta/a/imagen.pam}} > {{ruta/a/archivo_de_salida.pam}}`