technical_guide/base.rst - Incorrect descriptions

[John Bradshaw]

Two incorrect descriptions in technical_guide/base.rst.

Need someone with code experience to check this one...
1. Horizontal delta, think it should be "positive is leftward" (and neg. is rightward) - needs checked with code
2. Vertical delta, should be up/down (not left), also need to know if positive is up or down.
3. Perhaps bvz should be defined in full?
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:bvr_delta_horz: BVR Horz. Delta (mm), float

    *horiz. delta in mm 1.2 will print the bvz 1.2mm lefter*
-------------
:bvr_delta_vert: BVR Vert. Delta (mm), float

    *vert. delta in mm 1.2 will print the bvz 1.2mm lefter*
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[John Bradshaw (john-johnbradshaw)]

3. Perhaps ** bvr ** should be defined in full?