Under the opencc folder ,these are the opencc configuration files.

the following three files are currently been used in GoldenDict.
```
s2tw.json
s2hk.json
t2s.json
```
- how to specify other configuration files?

1. create a custom file ,such as custom.txt

![image](https://user-images.githubusercontent.com/105986/192209053-82f316ca-8657-4a59-af50-6e704d155fad.png)

2. modify the \*.json file, add add the new custom.txt to the configuration .

![image](https://user-images.githubusercontent.com/105986/192209129-ebc9efe7-ce82-4d4d-ad52-1b3c33eaf270.png)


any other valid opencc configuration solutions should also work here.
