[FEATURE]: Add a help message to reload shell configuration after install

[Mr-Sunglasses]

Feature hasn't been suggested before.

• [x] I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

After installing opencode, the shell configuration needs to be reloaded before it can be used. To make this easier for users, added a helpful message that guides users to reload their shell configuration.