Fix History paragraphs formatting

[otagi]

The History section in the About page does not format its paragraphs correctly:

This is due to newlines in the HAML source. HAML is indentation-sensitive (unlike raw HTML), so these newlines are interpreted as new paragraphs.

Each paragraph content should be typed in 1 line, without newlines. Or use special HAML escape characters if you really want to break the lines in the source code.