Iss 639 clarify contributors

[alex-cit]

fix #639
related to #617

• specific headline added for Contributors (https://merginmaps.com/docs/manage/subscriptions/) for better search
• which members and guests are considered to be contributors added to https://merginmaps.com/docs/manage/permissions/#workspace-members-and-guests
• updated dashboard screenshot to display where it is possible to check the current number of contributors https://merginmaps.com/docs/manage/dashboard/#members
• renamed the Contribute page https://merginmaps.com/docs/misc/contribute/ to Get Involved to avoid confusion in the search + updated the content (added link to LinkedIn, renamed twitter to X, etc)
• added component ServerCloudNameLink that translates to Mergin Maps Cloud with a link to merginmaps.com

[tomasMizera]

Can we add an info about additional storage? Something like

Suggested change

	Subscriptions are based on the number of *contributors* on the workspace. Per each contributor seat, you get 1 GB of storage. Storage is shared across the whole workspace.
	Subscriptions are based on the number of *contributors* on the workspace. Per each contributor seat, you get 1 GB of storage. Storage is shared across the whole workspace. You can get even more storage, just reach out to our team at <sales> and we will help you to set it up.

[alex-cit]

Added 👍