fix(toggleterm-manager-nvim): add missing keybindings documented

[LumenYoung]

📑 Description

As described in the title, I added two set of keybindings for the telescope interface, which were already documented in the README, but the insert mode keybindings were mistakenly removed during the handling of my initial PR. Therefore this pr try to fix this problem by reintroducing the keybindings.

ℹ Additional Information

[github-actions[bot]]

Review Checklist

Does this PR follow the [Contribution Guidelines](development guidelines)? Following is a partial checklist:

Proper conventional commit scoping:

• If you are adding a new plugin, the scope would be the name of the category it is being added into. ex. feat(utility): added noice.nvim plugin

• If you are modifying a pre-existing plugin or pack, the scope would be the name of the plugin folder. ex. fix(noice-nvim): fix LSP handler error

• [x] Pull request title has the appropriate conventional commit type and scope where the scope is the name of the pre-existing directory in the project as described above

• [x] README is properly formatted and uses fenced in links with <url> unless they are inside a [title](url)

• [x] Proper usage of opts table rather than setting things up with the config function.