Add same font-family on synopsis as on code

[strowk]

Changes

• add 'font-family' to synopsis class that is same as for 'code' elements

Context

This makes sure that spaces inserted between 'code' elements have the same size as text inside of 'code' elements, otherwise spaces look tiny and words in commands such as 'git merge' visually look almost touching each other.

Before:

After:

[dscho]

@jnavila I'll defer to you, seeing that this change potentially clashes with your ongoing efforts to improve the synopses.