* add CONTRIBUTING-de.md with German contributing guidelines.
* edit typos in CONTRIBUTING.md.
* add link to German contributing guide to language list in other contribution files, re-order list alphabetically.
* switch back the order of English and French language links in all Contribution Guidelines.
* eliminate extra spaces and put spaces in the correct positions.
* Create CONTRIBUTING-es.md
Translate to spanish
https://github.com/EbookFoundation/free-programming-books/blob/master/CONTRIBUTING.md
* Add english title anchors and other formattings
- Indent code blocks placed inside lists
- Add original (English) bookmarks above each title to allow change between language easily
- Minor text translation improvements
* Link to CONTRIBUTING-es.md
* Link to CONTRIBUTING-es.md
* Link to CONTRIBUTING-es.md
* Link to CONTRIBUTING-es.md
* Link to CONTRIBUTING-es.md