minor documentation update on SIGINT handling

doc/bashref.texi

@@ -3549,6 +3549,37 @@ which a trap has been set will cause the @code{wait} builtin to return
 immediately with an exit status greater than 128, immediately after
 which the trap is executed.
 
+When job control is not enabled, and Bash is waiting for a foreground
+command to complete, the shell receives keyboard-generated signals
+such as @code{SIGINT} (usually generated by @samp{^C}) that users
+commonly intend to send to that command.
+This happens because the shell and the command are in the same process
+group as the terminal, and @samp{^C} sends @code{SIGINT} to all processes
+in that process group.
+See @ref{Job Control}, for a more in-depth discussion of process groups.
+
+When Bash is running without job control enabled and receives @code{SIGINT}
+while waiting for a foreground command, it waits until that foreground
+command terminates and then decides what to do about the @code{SIGINT}:
+
+@enumerate
+@item
+If the command terminates due to the @code{SIGINT}, Bash concludes
+that the user meant to end the entire script, and acts on the
+@code{SIGINT} (e.g., by running a @code{SIGINT} trap or exiting itself);
+
+@item
+If the pipeline does not terminate due to @code{SIGINT}, the program
+handled the @code{SIGINT} itself and did not treat it as a fatal signal.
+In that case, Bash does not treat @code{SIGINT} as a fatal signal,
+either, instead assuming that the @code{SIGINT} was used as part of the
+program's normal operation (e.g., @command{emacs} uses it to abort editing
+commands) or deliberately discarded. However, Bash will run any
+trap set on @code{SIGINT}, as it does with any other trapped signal it
+receives while it is waiting for the foreground command to
+complete, for compatibility.
+@end enumerate
+
 @node Shell Scripts
 @section Shell Scripts
 @cindex shell script