shuf: document new benchmark category

src/uu/shuf/BENCHMARKING.md

@@ -28,11 +28,11 @@ a range of numbers to randomly sample from. An example of a command that works
 well for testing:
 
 ```shell
-hyperfine --warmup 10 "target/release/shuf -i 0-10000000"
+hyperfine --warmup 10 "target/release/shuf -i 0-10000000 > /dev/null"
 ```
 
 To measure the time taken by shuffling an input file, the following command can
-be used::
+be used:
 
 ```shell
 hyperfine --warmup 10 "target/release/shuf input.txt > /dev/null"
@@ -49,5 +49,14 @@ should be benchmarked separately. In this case, we have to pass the `-n` flag or
 the command will run forever. An example of a hyperfine command is
 
 ```shell
-hyperfine --warmup 10 "target/release/shuf -r -n 10000000 -i 0-1000"
+hyperfine --warmup 10 "target/release/shuf -r -n 10000000 -i 0-1000 > /dev/null"
+```
+
+## With huge interval ranges
+
+When `shuf` runs with huge interval ranges, special care must be taken, so it
+should be benchmarked separately also. An example of a hyperfine command is
+
+```shell
+hyperfine --warmup 10 "target/release/shuf -n 100 -i 1000-2000000000 > /dev/null"
 ```