Core register R_TIMESTAMP_OFFSET not implemented

[bruno-f-cruz]

The current schema does not implement the R_TIMESTAMP_OFFSET register. This register is defined in the current protocol version and should thus be supported in the core schema and core package.

[bruno-f-cruz]

Addressed in #178 by deprecating the register and calling it "Reserved".

However, for consistency, we should remove all references to the register from the spec. For instance:

protocol/Device.md

Line 65 in 9b32cfe

|[`R_TIMESTAMP_OFFSET`](#r_timestamp_offset-u8--clock-calibration-offset)|No|No|U8|015|b)|Configures an offset for Timestamp updates|Deprecated|

@glopesdev What do you think?

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this is also related to #197