docs: improve with symbol show

[shenxiangzhuang]

Docs preview

Checklist

• [x] I have read the CONTRIBUTING document
• [x] I hereby agree to the terms of either individual CLA available at: https://toloka.ai/legal/cla_individual or corporate CLA available at: https://toloka.ai/legal/cla_corporate, whichever is applicable to me, as it pertains to direct contributions to crowd-kit only
• [ ] My change requires a change to the documentation
• [ ] I have updated the documentation accordingly
• [ ] I have added tests to cover my changes
• [x] All new and existing tests passed