Change font size for API reference entries

[wojciechczerniak]

Too big font sizes exaggerate the meaning for some properties over the others. Quote from handsontable/#5136

Correct CSS. "Types" in tables are bigger than the other content. See this here: https://docs.handsontable.com/pro/3.0.0/ManualColumnFreeze.html#freezeColumn (font size 15px instead of 13px). Be careful though as it's a global setting and we probably need to override it these particular occurences. Also, a word "Properties" should be much smaller (now it's 24px and should be 14px). Additionally, change the size of the Return parameters section: https://docs.handsontable.com/pro/3.0.0/AutoColumnSize.html#getFirstVisibleColumn