Make 1 more prominent in the doc

doc/chapters/configuration.texi

@@ -567,7 +567,7 @@ as it emulates devices that have a limited amount of memory.
 @end defvr
 
 @defvr {Environment variable} STARPU_GENERATE_TRACE
-When set to 1, this variable indicates that StarPU should automatically
+When set to @code{1}, this variable indicates that StarPU should automatically
 generate a Paje trace when @code{starpu_shutdown()} is called.
 @end defvr
 

doc/chapters/perf-feedback.texi

@@ -295,7 +295,7 @@ generate a trace in the Paje format by calling:
 @end example
 
 Or alternatively, setting the @code{STARPU_GENERATE_TRACE} environment variable
-to 1 before application execution will make StarPU do it automatically at
+to @code{1} before application execution will make StarPU do it automatically at
 application shutdown.
 
 This will create a @code{paje.trace} file in the current directory that