doc: update writing-and-running-benchmarks.md

Refs: 368517c

PR-URL: #20379
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

doc/guides/writing-and-running-benchmarks.md

@@ -202,12 +202,11 @@ For analysing the benchmark results use the `compare.R` tool.
 ```console
 $ cat compare-pr-5134.csv | Rscript benchmark/compare.R
 
-                                                                                      improvement confidence      p.value
-string_decoder/string-decoder.js n=250000 chunk=1024 inlen=1024 encoding=ascii           12.46 %         *** 1.165345e-04
-string_decoder/string-decoder.js n=250000 chunk=1024 inlen=1024 encoding=base64-ascii    24.70 %         *** 1.820615e-15
-string_decoder/string-decoder.js n=250000 chunk=1024 inlen=1024 encoding=base64-utf8     23.60 %         *** 2.105625e-12
-string_decoder/string-decoder.js n=250000 chunk=1024 inlen=1024 encoding=utf8            14.04 %         *** 1.291105e-07
-string_decoder/string-decoder.js n=250000 chunk=1024 inlen=128  encoding=ascii            6.70 %           * 2.928003e-02
+                                                                                             confidence improvement accuracy (*)    (**)   (***)
+ string_decoder/string-decoder.js n=2500000 chunkLen=16 inLen=128 encoding='ascii'                  ***     -3.76 %       ±1.36%  ±1.82%  ±2.40%
+ string_decoder/string-decoder.js n=2500000 chunkLen=16 inLen=128 encoding='utf8'                    **     -0.81 %       ±0.53%  ±0.71%  ±0.93%
+ string_decoder/string-decoder.js n=2500000 chunkLen=16 inLen=32 encoding='ascii'                   ***     -2.70 %       ±0.83%  ±1.11%  ±1.45%
+ string_decoder/string-decoder.js n=2500000 chunkLen=16 inLen=32 encoding='base64-ascii'            ***     -1.57 %       ±0.83%  ±1.11%  ±1.46%
 ...
 ```
 
@@ -241,14 +240,13 @@ results afterwards using tools such as `sed` or `grep`. In the `sed` case be
 sure to keep the first line since that contains the header information.
 
 ```console
-$ cat compare-pr-5134.csv | sed '1p;/encoding=ascii/!d' | Rscript benchmark/compare.R --plot compare-plot.png
-
-                                                                               improvement confidence      p.value
-string_decoder/string-decoder.js n=250000 chunk=1024 inlen=1024 encoding=ascii    12.46 %         *** 1.165345e-04
-string_decoder/string-decoder.js n=250000 chunk=1024 inlen=128 encoding=ascii      6.70 %           * 2.928003e-02
-string_decoder/string-decoder.js n=250000 chunk=1024 inlen=32 encoding=ascii       7.47 %         *** 5.780583e-04
-string_decoder/string-decoder.js n=250000 chunk=16 inlen=1024 encoding=ascii       8.94 %         *** 1.788579e-04
-string_decoder/string-decoder.js n=250000 chunk=16 inlen=128 encoding=ascii       10.54 %         *** 4.016172e-05
+$ cat compare-pr-5134.csv | sed '1p;/encoding='"'"ascii"'"'/!d' | Rscript benchmark/compare.R --plot compare-plot.png
+
+                                                                                      confidence improvement accuracy (*)    (**)   (***)
+ string_decoder/string-decoder.js n=2500000 chunkLen=16 inLen=128 encoding='ascii'           ***     -3.76 %       ±1.36%  ±1.82%  ±2.40%
+ string_decoder/string-decoder.js n=2500000 chunkLen=16 inLen=32 encoding='ascii'            ***     -2.70 %       ±0.83%  ±1.11%  ±1.45%
+ string_decoder/string-decoder.js n=2500000 chunkLen=16 inLen=4096 encoding='ascii'          ***     -4.06 %       ±0.31%  ±0.41%  ±0.54%
+ string_decoder/string-decoder.js n=2500000 chunkLen=256 inLen=1024 encoding='ascii'         ***     -1.42 %       ±0.58%  ±0.77%  ±1.01%
 ...
 ```