Add Doxygen documentation to SymbolTable's contents. Some parameters were renamed to make their purpose easier to understand. Change-Id: Ia4f18bf60d3d8eab7a775f34f553d420816d62b9 Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/43248 Tested-by: kokoro <noreply+kokoro@google.com> Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com> Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>