Fix RFC3339 typo in docs

[IJMacD]

- What I did Edited the docs

- How I did it N/A

- How to verify it N/A

- Description for the changelog

Fix RFC3339 typo in docs

- A picture of a cute animal (not mandatory but encouraged)

[codecov-commenter]

Codecov Report

Merging #3975 (bad6157) into master (d0a4b6f) will increase coverage by 58.82%. The diff coverage is n/a.

Additional details and impacted files

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##           master    #3975       +/-   ##
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+ Coverage        0   58.82%   +58.82%     
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  Files           0      285      +285     
  Lines           0    24683    +24683     
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+ Hits            0    14521    +14521     
- Misses          0     9279     +9279     
- Partials        0      883      +883     

[thaJeztah]

I was wondering of some of this was intentional (but admitted; I always get confused on Go's time format strings); also because Z is described further down, and looking at https://github.com/moby/moby/blob/17b2c89116a3fa9ebfe24b38000365096dc8bdc2/api/types/time/timestamp.go#L11-L18

// These are additional predefined layouts for use in Time.Format and Time.Parse
// with --since and --until parameters for `docker logs` and `docker events`
const (
	rFC3339Local     = "2006-01-02T15:04:05"           // RFC3339 with local timezone
	rFC3339NanoLocal = "2006-01-02T15:04:05.999999999" // RFC3339Nano with local timezone
	dateWithZone     = "2006-01-02Z07:00"              // RFC3339 with time at 00:00:00
	dateLocal        = "2006-01-02"                    // RFC3339 with local timezone and time at 00:00:00
)

[vvoland]

Yeah I looked into it, it's a bit misleading because 2006-01-02Z07:00 is expected to parse dates with timezone, but without time. So: time.Parse("2006-01-02Z07:00", "2023-01-18Z16:02") = error time.Parse("2006-01-02Z07:00", "2023-01-18+03:00") = ok, 2023-01-18, time 00:00, offset +3h

[IJMacD]

@vvoland I have pushed changes to the other files you mentioned.

I agree that Go's time format specifiers and accompanying documentation in incredibly misleading and leads to slip ups like this propagating across the ecosystem.

2006-01-02Z07:00 is valid as a format specifier in Go; it is never a valid value.

The change in this pull request is the minimal diff to get valid ISO 8601 values in the Docker docs i.e. 2006-01-02T07:00 changing Z to T to make a combined date-time representation (at 7 am local time)

I can't be sure but the Go docs seem to suggest the format specifier 2006-01-02Z07:00 would accept the following values implying 00:00:00 in UTC or local time. However, neither of the following is valid under ISO 8601 [1].

{ 2006-01-02Z, 2006-01-02+07:00 }

[Ref 1: ISO 8601-1:2019 § 5.4.2.1]