Add logo config, and complete edit page to user guide

[shawnlinxl]

1. In the user guide, I've added a section for adding logo:

• this part might be redundant, as it's already in Sphinx's documentation.
• my argument for still having it is some user may not be fluent enough in Sphinx, while still want to use pydata sphinx theme, which is a great theme. Without setting the logo, the navbar actually becomes not that great looking. By being explicit about the logo configuration in user guide, it makes it easier for user to find this setting.

2. Also, I've added additional instruction for including "edit this page". I believe this is necessary for edit this page to work:

html_theme_options = {
    "use_edit_page_button": True,
}

[jorisvandenbossche]

this part might be redundant, as it's already in Sphinx's documentation.

It's indeed certainly useful for people less familiar with sphinx!

[jorisvandenbossche]

Thanks a lot!