Fix typo and formatting

Author: SimonBaeumer

CHANGELOG.md

@@ -1,7 +1,7 @@
 # v1.3.0
 
  - Added `xml` assertion to `stdout` and `stderr`
- - Added `json` assertin to `stdout` and `stderr`
+ - Added `json` assertion to `stdout` and `stderr`
  - Remove `cmd` pkg and use `github.com/SimonBaeumer/cmd@v1.1.0` instead
  - Add `inherit-env` to `config`, it enables inheriting the parent's env variables.