remove parasitic words from descriptions

[VladimirAlexiev]

Term descriptions include a lot of parasitic words, please remove them.

• If needed, I can find a formal rule that says "definiens should not repeat the definiendum".
• Furthermore, semantic terms are intended to represent real-world entities, not "refer" to them

Examples:

• "This property refers to the entity responsible for producing the dataset." ->
  "Agent responsible for producing the dataset"
• "This property contains a free-text account of the Dataset. This property can be repeated for parallel language versions of the description." ->
  "free-text account of the Dataset, can be repeated for parallel language versions of the description."