README: Add link to gem5-aladdin, fix typos.
README: Add link to gem5-aladdin, fix typos.

Change-Id: I1b43f44a5b89d722741d3260412ac9440f6e2053

giosalv/526-aladdin,giosalv/526-aladdin,giosalv/526-aladdin,giosalv/526-aladdin