Correct bottom anchor x position for vav-vav/yod-yod digraphs (#38)

[markhdavid]

For all three families (Sans, Serif, Rashi) and across all layers, this commit adds the "bottom" anchor at the correct x position for double-yod and corrects it for double-vav. The adjustment ensures the x position is now accurately placed halfway between the bottom anchor's x position on each of the subletters, with the Y position at 0 (baseline).

Tested by regenerating TTFs via the Glyphs App (File > Export) for each family, then running hb-view commands ala instructions in issue, but extended test to every weight generated for all 3 families (Sans/Rashi/Serif). Then visually inspected every resulting .png file, confirming the corrections were successful and visually consistent across all variants.

[markhdavid]

Here is a sampling of tested families/weights, specifically those that had been shown in the Screenshot section of issue #38, showing correct anchor x position for the digraphs:

Sans Thin:

Sans Extra Light:

Sans Light:

Rashi Regular:

[simoncozens]

Thank you very much, looks good to me!