Page rework

[Freymaurer]

this is currently under development and will be püart of this PR: https://github.com/nfdi4plants/nfdi4plants.github.io/pull/152

• [x] About -> Community and partner; still missing content.
• [x] About -> Testimonials; formatting
• [x] About -> nfdi; missing "read more"
• [x] information -> news; fix news link
• [x] information -> events; fix events link
• [x] information -> knowledge base; fix link
• [ ] service -> sitemap not compatible with word doc(!)
• [ ] service -> arc; still needs work
• [x] service -> dataplan; fix link
• [x] service -> training; fix link
• [x] service -> templates; fix link
• [x] service -> data publication; add link for ARChive
• [x] service -> collect and structure; fix links and add file to sitemap!
• [x] #154
• [x] #155
• [ ] resources -> galaxy; missing link
• [x] resources -> for developers; formatting + subcontent
• [ ] resources -> styleguide; missing
• [ ] participation -> how to start; missing
• [x] support -> helpdesk; missing link
• [ ] support -> rdm; missing link to arc-rdm.org
• [x] support -> custom training; missing mailto: link
• [ ] support -> user support meeting from word file not on sitemap! not done!
• [ ] fix image aspect ratios

[kMutagene]

Note that the word doc and the repo is heavily out-of-sync, as it is to be expected.

From now on i suggest documenting everything in this repo.

Also, the sitemap is out-of sync, and some subpages have missing content.