Update README.md

README.md

@@ -118,7 +118,9 @@ For example, the last cycle of Illumina sequencing is uaually with low quality,
 * For read2 of PE data, the front/tail trimming settings are given with `-F, --trim_front2` and `-T, --trim_tail2`. But if these options are not specified, they will be as same as read1 options, which means `trim_front2 = trim_front1` and `trim_tail2 = trim_tail1`.
 
 # polyG tail trimming
-For Illumina NextSeq/NovaSeq data, `polyG` can happen in read tails since `G` means no signal in the Illumina two-color systems. `fastp` can detect the polyG in read tails and trim them. This feature is enabled for NextSeq/NovaSeq data by default, and you can specify `-g` or `--trim_poly_g` to enable it for any data, or specify `-G` or `--disable_trim_poly_g` to disable it. NextSeq/NovaSeq data is detected by the machine ID in the FASTQ records.
+For Illumina NextSeq/NovaSeq data, `polyG` can happen in read tails since `G` means no signal in the Illumina two-color systems. `fastp` can detect the polyG in read tails and trim them. This feature is enabled for NextSeq/NovaSeq data by default, and you can specify `-g` or `--trim_poly_g` to enable it for any data, or specify `-G` or `--disable_trim_poly_g` to disable it. NextSeq/NovaSeq data is detected by the machine ID in the FASTQ records.   
+
+A minimum length can be set with `<poly_g_min_len>` for `fastp` to detect polyG. This value is 10 by default.
 
 # unique molecular identifer (UMI) processing
 UMI is useful for duplication elimination and error correction based on generating consensus of reads originated from a same DNA fragment. It's usually used in deep sequencing applications like ctDNA sequencing. Commonly for Illumina platforms, UMIs can be integrated in two different places: `index` or head of `read`.  
@@ -196,7 +198,6 @@ options:
   # polyG tail trimming, useful for NextSeq/NovaSeq data
   -g, --trim_poly_g                  force polyG tail trimming, by default trimming is automatically enabled for Illumina NextSeq/NovaSeq data
       --poly_g_min_len                 the minimum length to detect polyG in the read tail. 10 by default. (int [=10])
-
   -G, --disable_trim_poly_g          disable polyG tail trimming, by default trimming is automatically enabled for Illumina NextSeq/NovaSeq data
   
   # per read cutting by quality options