content.tex: convert ascii tables into tabulars

Note: html output for tabular looks weird; not sure what is wrong there.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
content.tex: Use description for status bits.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
content.tex: Use description for legacy and transitional definitions.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
content.tex: Use description for feature bits.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
content.tex: Use tabulars for request queues.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>