vertical metrics doc should be updated to Marc's recommendations

[thundernixon]

@m4rc1e, are you still confident in your recommendations at fonttools/fontbakery#2164 (comment) ?

They just helped me fix a bug in Inter (rsms/inter#141).

To do:

• If it looks good to Marc, I can update the vertical metrics specs.

• We should also verify that a gftools script exists to fix this properly.

[thundernixon]

P.S.: @davelab6, would it be possible for me to get a higher access level on this repo? I'd like to assign this task to myself.

[davelab6]

would it be possible for me to get a higher access level on this repo?

You got it

[weiweihuanghuang]

The vertical metrics doc is quite different to how it's done here https://github.com/googlefonts/gf-glyphs-scripts/blob/master/Google%20Fonts/initial_vertmetrics.py is this the same issue?