Update README.md to keep using SC font

assets/fonts/SourceHanSans.ttc has been upgraded so now
SourceHanSans11.ttf is the Simplified Chinese one.

README.md

@@ -11,7 +11,7 @@
 ```bash
 wget https://bf.mengyan1223.wang/assets/fonts/{SourceHanSans.ttc,ttc2ttf.py}
 python3 ttc2ttf.py SourceHanSans.ttc
-./wordfreq.py -i example.in -o example.png -p n,ne -f SourceHanSans10.ttf -t 60
+./wordfreq.py -i example.in -o example.png -p n,ne -f SourceHanSans11.ttf -t 60
 ```
 
 You should use Source Han Sans font under the terms of SIL Open Font License 1.1.