fix(translations): improve Spanish translations (#12555)

There are still things to improve.

- We're inconsistent with our use of capital letters. There are still
sentences where every word starts with a capital letter, and it looks
ugly (this also happens in English, but to a lesser extent).
- We're inconsistent with the use of punctuation at the end.
- Sentences with variables like {{count}} can result in inconsistencies
if it's 1 and the noun is plural.
- The same thing happens in Spanish, but also with gender. It's
impossible to know without the context in which it's used.

---------

Co-authored-by: Paul Popus <paul@payloadcms.com>

test/admin/e2e/general/e2e.spec.ts

@@ -677,7 +677,7 @@ describe('General', () => {
 
       await expect(page.locator('.step-nav a').first().locator('span')).toHaveAttribute(
         'title',
-        'Tablero',
+        'Panel de Control',
       )
 
       await field.click()