The purpose of this document is to give technical information on the selected STACK and technology to be used to support the application.
Overall STACK Information
If the application uses an overall STACK implementation like MEAN or .NET Core then this is the place to talk about it. Versions are important as you may be asked to support this application 10 years later. You need as much detailed information here.
Database
Information about what database is being used? where is it hosted? what is the protocol to get in? What tools are you using?
Web Servers
What type of hosting is being used? IIS? Apache? Versions? Where is the hosting (service?), What accounts? What kind of service does your host have? How do you access the service?
Language
There may be multiple languages, but you need to document all languages used and in what portion of the application.
Framework
The framework may be redundant and included in the overall STACK, but you may also be using multiple libraries and parts of other frameworks. Common frameworks are .NET Core, Node.js, REACT, etc… Here are the top ones in 2020 https://medium.com/front-end-weekly/10-most-popular-web-frameworks-in-2020-167b9103e08a
Miscellaneous
Any other information goes here. Basically, if you have to tell someone something to get started working in your application, it belongs in the documentation.