some doc errors

[seedpower]

some doc errors

[sonarcloud[bot]]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.0% Duplication

[codecov[bot]]

Codecov Report

Base: 78.40% // Head: 78.40% // No change to project coverage :thumbsup:

Coverage data is based on head (01c78d7) compared to base (c68c2b4). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #394 +/- ## ======================================== Coverage 78.40% 78.40% ======================================== Files 179 179 Lines 14687 14687 ======================================== Hits 11516 11516 Misses 3171 3171 ``` | [Impacted Files](https://codecov.io/gh/cuihantao/andes/pull/394?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Hantao+Cui) | Coverage Δ | | |---|---|---| | [andes/system.py](https://codecov.io/gh/cuihantao/andes/pull/394/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Hantao+Cui#diff-YW5kZXMvc3lzdGVtLnB5) | `79.27% <ø> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Hantao+Cui). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Hantao+Cui)

:umbrella: View full report at Codecov.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.

[cuihantao]

Thank you!