[Documentation] createDataTable: horizontal borders are not stable

[J-Sek]

Steps:

• open docs » Market overview example
• or playground - make sure to reduce width, so that bottom scrollbar appears
• type 'a' in search

Notes:

• hovering over rows fixes the missing border
• replacing divide-y divide-divider on <tbody> with border-b border-divider on <td> helps a bit, but border still disappears on 110% page zoom
• I was able to reproduce it on Chromium-based browsers (FF and Webkit work fine)

Expected:

• borders to be stable - visible all the time, not disappearing randomly