Implemented all Greek string translations (Native)

[laiosg]

• Implemented the Greek (el) translations for the Keep Android Open website by adding translations for all untranslated user-facing strings (native speaker)
• Made small fixes in the previous translation (mostly consistency issues, such as a word with two ways to spell it being written in both ways through the document instead of just one)
• Reviewed the strings, made changes to the flow of translated sentences
• Validated the translation file for proper YAML formatting

Please note that due to Greek being a rather verbose language and X/Bluesky having strict character limits (which are already used up in part by the URL and/or hashtag included in each string), some X and Bluesky have been slightly rephrased or shortened, while keeping the original meaning intact.

[marcprux]

Fantastic contribution, thanks! Please verify that it looks OK to you: https://keepandroidopen.org/el/

[laiosg]

Glad to have been of help, raising awareness about this is important!
Everything looks fine, I noticed a missing translation for a string, I will be fixing this issue soon and making a new PR.