[documentation] Add documentation from v0.3.6 onwards

[darkhz]

Since v0.3.6, changes have not been documented and features must be added with screenshots, gifs and descriptions.
Contributions/PRs will be reviewed before merging.

Follow the format according to how the previous documentation has been added.
Each new feature must have its own separate page.

The following features must be documented:

Queue

• Recommendations tab
• Audio/Video switching
• Shuffle mode

Media Fetcher

• Opening the fetcher
• Reload, Cancel each/all loading media items
• Clearing the fetcher

Custom Seeker

• Opening the seek dialog
• Navigate between inputs
• Seek by relative/absolute positions

Theming

• Open the theme selector
• Applying a theme

A brief documentation is here: https://github.com/darkhz/invidtui/tree/theme

Channel

• Releases tab

Keybindings

New keybindings must be added within the keybindings table for:

• Queue
• Fetcher
• Custom Seeker
• Theme Selector

New keybinding names:

• KeySelect -> Enter

New defaults:

• KeyLoadMore -> .

Certain keybinding names have changed:

• KeySwitchTab to KeySwitch