Update voc4cat-description and add sample & pid4cat concepts

[dalito]

This PR

• Improves the old definition of the ConceptScheme voc4cat. This definition shows up as "description" in the header of the documentation. Note the use of markdown in Excel to add a correctly rendered link to the generated page.
• Adds concepts related to "sample". A concept "sample" is not added because a sample can be physical or non-physical. Therefore, this PR adds three concept and adds a reference to the broader sample definition in SOSA.
  • material sample
  • spatio-temporal sample
  • statistical sample
• Adds concepts for/from pid4cat
  • Various relations to express connections between two resources (these can be used beyond PIDs), see resource relation and narrower concepts
  • A PID-specific classification of categories describing what type of resource the PID links to see PID resource categories and narrower concepts
  • A pid4cat-specific classification of PID states, see pid4cat status and narrower concepts
• Removes turtle file https://w3id.org/nfdi4cat/voc4cat_0007037 accidentally added in addition of a few new concepts #112
• Changes pref.label of voc4cat:0007038 to "sample mass" (from just "mass"). Also improved its definition (weight≠mass).
• Fix typos in 2 concepts (continous -> continuous)

Closes #115
Closes #116

[dalito]

To track the mapping bug, I created an issue nfdi4cat/voc4cat-tool#241

[dalito]

@nmoust This is now ready for review. I removed the mappings and created #118 to remind us on adding them when the bug is fixed.

[nmoust]

There are only a few small changes needed I think:

URI	Concept	Change proposed
voc4cat_0005016	data object	Is there an extra space between the two sentences in the definition?
voc4cat_0005018	data relation	Typo: relatons
voc4cat_0005051	pid4catstatus	Should it be pid4cat status?
voc4cat_0005054	obsoleted	Do we need "(PID)" in the definition? Because in the other relations we only have "persistent identifier"
voc4cat_0005058	statistical sample	Typo: selecetion

[dalito]

Checking the docs-preview for this PR I also recognized some issues with the hierarchy. This, some other typos and all of @nmoust´s points from the review are fixed now.

I also changed the definitions of the children of "PID resource categories" to start with "A PID resource category...". This adds some duplication but it helps to understand the meaning of the concepts without checking their location in the hierarchy. I believe such extended definition is especially useful for concepts that have a general word like sample as preferred label.

[nmoust]

@dalito I think that everything looks good now. I will approve the changes.

[nmoust]

@dalito: Shall I click "Rebase and merge" after the review or would you like to do it?

[dalito]

I will do it.

One point I am still thinking about is adding qualifiers like so sample (PID resource category). This is an option we mention in the guidelines.

Update: I decided against adding classifiers, as their presence interferes with other applications that want to use concept definitions. For this reason, using qualifiers should be limited to a few exceptional cases like the one in the guidelines.