Add Gapher (OpenSource UML, SysML, RAAML, and C4 modeler)

[sboisson]

Gaphor is a UML, SysML, RAAML, and C4 modeling application. It is designed to be easy to use, while still being powerful. Gaphor implements a fully-compliant UML 2 data model, so it is much more than a picture drawing tool. You can use Gaphor to quickly visualize different aspects of a system as well as create complete, highly complex models.

https://gaphor.org
https://github.com/gaphor/gaphor

[shubhamgrg04]

Adding Gaphor to others section, as needs to be evaluated in future. Ther are couple of issues currently which makes it less easy to use:

• it doesn't have a web version, which becomes really handy
• the website is showing chinese text, although language selected is english