revisit and align the definition of Adjusted data

[stephanbracke]

Adjusted data is defined on different places and in different manners.
It needs to be aligned

• https://intermagnet.org/faq/03.intermagnet-data-types.html
• https://tech-man.intermagnet.org/stable/chapters/submitdata/introduction.html#data-types (seems the most correct one)
• https://tech-man.intermagnet.org/stable/appendices/terminology.html#term-ADJUSTED-Data