I did not raise thus issue to start the duscussion on the training requirement again. I remember we recently had this in the forum and it was concluded it depended on what the company defined as the training needed to justify that the employee is qualified for his/her job.
In this case, if the company has determined that the employee needs to be aware of this even minor change of the WI to execute its task according to the specification, it needs a training record that provides evidence that this information was transferred (one way or the other). Therefore you like to refer to the amendment. For that purpose the amendment has to be identified by other means than a version number. Compare of how ISO identifies amendments to standards by adding a1, a2 etc for each subsequent amendment.
Alternatively, if you publish your WI with tracked changes you do not need to bother with amendments but just raise the version. The change can easily be identified and trained.
Second alternative: prevent long WIs. WIs should be limited to what one person can do, at one location, a one point in time. WIs ofter contain information not required to execute the task. That should be presented in documents like policies and procedures. Also the product or process specification (limits, instrument settings) needed for the task can be defined in seperate documents where practical. If your WI are as short as max 5 pages you probably would not have started this discussion as the maintainability of your QMS does not initiate alternative approaches.