Missing examples for some tags in typography docs

[cvrebert]

• <del> & <s>
• <ins>
• <u>
• <mark>
• <samp>
• <var>

[zlatanvasovic]

• <del>, <s>, <ins>, <u> should go to typography
• Bootstrap doesn't have good styling for <mark> as it looks very weird with #000 color on yellow background 😟
• <samp> and <var> should recieve monospace font styling like for <code> and they should go in code section

[saas786]

+1

[page7]

mark backgroud color is too light...