Correct typos in documents

[yoshida-ryuhei]

Description

Correct typos in documents.

Type of change

• This change requires a documentation update

Checklist:

• [ ] My code follows the style guidelines of this project (You can use the linters)
• I have performed a self-review of my own code
• [ ] I have commented my code, particularly in hard-to-understand areas and hacks
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests to verify my fix or my feature
• [ ] New and existing unit tests pass locally with my changes

I am not sure that correcting this directory docs/_sources/ is adequate or not.
If I should correct another directory, plese let me know.

[narendasan]

Thanks for the fixes. However, you are editing the pre rendered docs and not the doc source (//docsrc). Just modifying the rst files will be sufficient. CI will build the docs for you

[yoshida-ryuhei]

Thanks for reviewing my pull request.
I overlooked the directory //docsrc folder. So, I will correct the //docsrc.

[yoshida-ryuhei]

Now I have changed the directory to correct the document.
I am happy if you review the code.

[narendasan]

LGTM