Correct NMI text in user manual

Created by: Silabs-ArjanB

"When a data bus fault occurs, the first detected fault will be latched and used for mcause when the NMI is taken. Any new bus faults occuring while an NMI is pending will be discarded. When the NMI handler is entered, new bus faults may be latched."

should be changed into:

"When a data bus fault occurs, the first detected fault will be latched and used for mcause when the NMI is taken. Any new data bus faults occuring while an NMI is pending will be discarded. When the NMI handler is entered, new data bus faults may be latched."