is_debugger_present: Fix unsupported statement-of-fact

The note in the description of `is_debugger_present` reads as a
statement of fact about the normatively implementation-defined
behaviour. Fix this to read as a statement of intent.

Author: Hubert Tong

source/diagnostics.tex

@@ -2493,12 +2493,13 @@
 \impldef{default semantics of \tcode{is_debugger_present}}.
 
 \begin{note}
-When tracing the execution of a program with a debugger, an implementation
-returns \tcode{true}. An implementation performs an immediate query, as needed,
-to determine if the program is traced by a debugger. On Windows or equivalent
-systems, this can be achieved by calling the \tcode{::IsDebuggerPresent()} Win32
-function. On POSIX, this can be achieved by checking for a tracer parent process,
-with best effort determination that such a tracer parent process is a debugger.
+It is intended that, when tracing the execution of a program with a debugger, an
+implementation returns \tcode{true} with the use of an immediate query, as
+needed, to determine if the program is being traced by a debugger. On Windows or
+equivalent systems, this can be achieved by calling the
+\tcode{::IsDebuggerPresent()} Win32 function. On POSIX, this can be achieved by
+checking for a tracer parent process, with best effort determination that such a
+tracer parent process is a debugger.
 \end{note}
 
 \end{itemdescr}