German Translation - Monero Site - Ready for merge

main:

• translated: de.yml - Status: peer-reviewed
• translated: lang\de\ - Status: peer-reviewed
• added: "de: Deutsch" in other ymls

resources: (These will not be included in this PR)

• untranslated: moneropedia - some terms added to match de.yml
• untranslated: user guides
• untranslated: developer guides

My thanks go to @rodolfo912 and his perseverance as well as to @rbrunner7 for their reviews and to @erciccione for his continued, inexhaustible support on everything considering translations and the usage of git.