update documentation

[koebel]

Description

update documentation

• better structure of content through TOC
• adding more detailed description of functionalities
• adding more information about installation for development and deployment
• adding information how to add DICOM Viewer to the ocis deployment example (referenced .yml file needs to be merged before this update is published!!!, see adding dicom-viewer.yml #67)

Related Issue

• Fixes Update documentation: prerequisites, including supported ocis-web versions and installation #64

Motivation and Context

make it easier for users understand benefits of the app and to install and use it

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added

[mmattel]

Just added a few commits for headline capitalisation we use on most repos (and in all over docs) 😃

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[koebel]

only merge after #67 has been merged

[S-Panta]

Also, it is necessary to update csp rules for di-com viewer(https://github.com/owncloud/awesome-ocis/blob/0138d4fd966fed78658e813eba6929fd4e4496aa/webApps/apps.json#L374) in https://github.com/owncloud/ocis/blob/master/deployments/examples/ocis_full/config/ocis/csp.yaml to make it work.