DOC: Add spaces before `:` to cancel bold
- [x] closes #47735
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

after add spaces rendering

![image](https://user-images.githubusercontent.com/25895405/180792393-ecd4575a-f3f1-4678-9c24-1050d951ade2.png)
 Thanks @Zeroto521 