ddb(4): improve wording

[imp]

Summary

Half of this has already been committed. Include wblock's changes that I somehow overlooked when this was originally done.

[• ian]

share/man/man4/ddb.4

1545

I would switch word order here to smooth the sentence flow...

... can be difficult to arrange in some setups, however, so ...

[imp]

Better wording inspired by Ian.

[wblock]

share/man/man4/ddb.4

1530

s/IMPI/IPMI/

1538

Avoid "you", and try to clear up the last part of the sentence:

Serial consoles can break to the debugger by sending a BREAK
condition on the serial line.  This requires a kernel built with
.Cd options BREAK_TO_DEBUGGER .

1543

s/or via a//

1550

This sentence is very long and difficult to follow. Best to split it up into shorter sentences.

Sending the break can be difficult or even happen spuriously in some setups.
An alternate method is to build a kernel with
.Cd options ALT_BREAK_TO_DEBUGGER .
With that kernel, the sequence of CR TILDE CTRL-B enters the debugger,
CR TILDE CTRL-P causes a panic instead of entering the ​debugger, and
CR TILDE CTRL-R causes an immediate reboot.

1551

In all these sequences, CR represents a Carriage Return and is usually
sent by pressing the Enter or Return key.

1554

CTRL-x is Control x, sent by pressing the Control key, then x, then releasing both.

There probably should be some markup on "x" to represent the key, also on the tilde in the previous sentence.
At this moment, I don't know exactly what that should be (brain is in a different namespace right now).

1557

s/may/can/, also use a compound adjective, and the final "the" is probably not needed:

The break-to-debugger behavior can also be enabled by setting

1561

As above:

The alt-break-to-debugger behavior can also be enabled by setting

1565

The debugger can be entered by setting

[imp]

wblock's changes