[reggen] Describe REGWEN properly for multi-registers #3614

Job	Run time
Lint (quick)	3m 28s
Build documentation	5m 5s
Lint (slow)	11m 18s
Verible lint	59s
Run OTBN crypto tests	20m 56s
Airgapped build	11m 33s
Run OTBN smoke Test	2m 35s
Verilated English Breakfast	7m 46s
Build Docker Containers	2m 58s
CW305's Bitstream	15m 59s
Build and test software	13m 48s
Verilated Earl Grey	1h 21m 9s
Earl Grey for CW310 / Build bitstream	1h 10m 48s
Earl Grey for CW310 Hyperdebug / Build bitstream	1h 12m 59s
Earl Grey for CW340 / Build bitstream	29m 32s
CW340 Test ROM Tests	0s
CW340 ROM Tests	0s
CW340 ROM_EXT Tests	0s
CW340 SiVal Tests	0s
CW340 Manufacturing Tests	0s
CW340 SiVal ROM_EXT Tests	0s
CW310 Test ROM Tests / FPGA test	3m 56s
CW310 ROM Tests / FPGA test	40m 39s
CW310 ROM_EXT Tests / FPGA test	6m 12s
Cache bitstreams to GCP	0s
CW310 SiVal ROM_EXT Tests / FPGA test	38m 5s
CW310 SiVal Tests / FPGA test	24m 42s
CW310 Manufacturing Tests / FPGA test	27m 21s
Verify FPGA jobs	23s
	8h 12m 11s

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