Remove mention of --message-format taking multiple values

[casey]

I tried passing multiple values to --message-format, as is mentioned in the docs, and it didn't work:

$ cargo test --message-format human,json
error: cannot specify two kinds of `message-format` arguments
$ cargo test --message-format human --message-format json
error: cannot specify two kinds of `message-format` arguments

It's entirely possible I misunderstood the docs, but just in case I didn't, I thought I'd open this PR to remove the bit that mentions that the flag accepts multiple values.

[rust-highfive]

r? @ehuss

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[ehuss]

Thanks for bringing this up! So, it does support multiple arguments, but only the json- prefixed ones. The code is here. Would you be willing to just extend the documentation to clarify that the multiple arguments only apply to the json fields, and that the json settings can't be combined with human and short?

Also, when updating the source for the man pages, they need to be rebuilt and the changes committed. The documentation for that is here.

[casey]

Thanks for bringing this up! So, it does support multiple arguments, but only the json- prefixed ones. The code is here.

Ah, I see.

Would you be willing to just extend the documentation to clarify that the multiple arguments only apply to the json fields, and that the json settings can't be combined with human and short?

I wasn't entirely sure how to best summarize this, because the rules are a little complicated, so I clarified what could be combined in the documentation for each value.

Also, when updating the source for the man pages, they need to be rebuilt and the changes committed. The documentation for that is here.

Done!

[ehuss]

Looks good, thanks!

@bors r+

[bors]

📌 Commit d174b77 has been approved by ehuss

[bors]

⌛ Testing commit d174b77 with merge 3e25c9d...

[bors]

☀️ Test successful - checks-actions
Approved by: ehuss
Pushing 3e25c9d to master...

[casey]

Thanks for merging!