Remove reference to some SSN terms

[alexrobin]

The SystemKind class and its subclasses were dropped from the latest SOSA/SSN draft so we need to revert to use the plain System classes identifiers for procedure types.

This is OK for us because the mere fact that they are in the procedures or systems collections indicate whether they are System instances or System kinds. We need to explain this.

[alexrobin]

Discussed during 10/17 telecon.

Will revert to using SOSA URIs for System and subclasses in Table 16: Procedure Types

[autermann]

There are even more changes, the http://www.w3.org/ns/sosa/ActuatingProcedure mentioned in Table 16 doesn't exist, it was called https://www.w3.org/ns/sosa/om#ActuationProcedure and now it seems to be gone: https://w3c.github.io/sdw-sosa-ssn/ssn/#OMS-New-Terms
Instead there is now a new http://www.w3.org/ns/sosa/oms/PreparationProcedure...

[alexrobin]

Discussed during 12/12 telecon.

We will use the following to the enum:

• http://www.w3.org/ns/sosa/Procedure
• http://www.w3.org/ns/sosa/oms/ObservingProcedure
• http://www.w3.org/ns/sosa/oms/Samplingrocedure
• http://www.w3.org/ns/sosa/oms/PreparationProcedure
• Will ask the SOSA/SSN WG about ActuatingProcedure