Syllabus: remove memory partitioning and add Heterogeneity

As per Luca's suggestion.

While at it, change the intro papers as well.

Signed-off-by: Emilio G. Cota <cota@braap.org>
candidacy: remove trailing period + whitespace after title

Signed-off-by: Emilio G. Cota <cota@braap.org>