Update docs for open and decode command, regenerate all docs

[hustcer]

Description

Update docs for open and decode command, regenerate all docs
Fix #4809

I have checked all the other extra_usage in nu v0.44, most of them were added in nu 0.59, except enter, autoenv, reduce. We don't support enter a file and autoenv yet, so they both could be ignored. And I don't understand the extra_usage of command reduce very well

Tests

Make sure you've run and fixed any issues with these commands:

• cargo fmt --all -- --check to check standard code formatting (cargo fmt --all applies these changes)
• cargo clippy --all --all-features -- -D warnings -D clippy::unwrap_used -A clippy::needless_collect to check that you're using the standard code style
• cargo build; cargo test --all --all-features to check that all the tests pass

[sophiajt]

thanks!

[fdncred]

ya, who knows what that reduce mess means. I get a little tired of people typing esoteric programmer lingo in the code base. it just makes it harder to understand for most people. like, it would be good to change all the predicate terms people see in help text and parameters to condition. condition is much more understandable I think.