doc: Fixed syntax error.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Added some packages to the copyable line.

Fixes: #3686

Signed-off-by: John Wilkins <john.wilkins@inktank.com>
doc: Added comments on --without-tcmalloc option when building Ceph.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>