readme and documentation improvements

[MisterHW]

Starting this issue to collect some notes regarding the project documentation. This may be an ongoing issue, or (depending on how it develops) be done at some point.

• add BOM viewing link http://htmlpreview.github.io/?https://github.com/Jana-Marie/temperature-logger/blob/main/bom/ibom.html to be able to directly view the latest version of the interactive BOM