[Reference][Form Types] Document "with_minutes" time/datetime option
Fix "versionadded" position
minor #3429 [Reference][Form Types] Document "with_minutes" time/datetime option (bicpi)

This PR was merged into the 2.3 branch.

Discussion
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[Reference][Form Types] Document "with_minutes" time/datetime option

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | yes
| Applies to    | 2.3+
| Fixed tickets | #3410 (task `time > with_minutes`)

The `datetime` field also has a `with_minutes` option.

Using the `single_text` widget type might not work as expected using `with_minutes=false` if the browser supports HTML5's `time` input type. Most browsers seem to only support `hh:mm` or `hh:mm:ss` formats for the value attribute (resetting the value to `--:--` if using an hour value only). This might not be the case for every browser because I couldn't find anything in the HTML5 spec that says a partial time cannot be an hour only. I've added a `caution` box for this.

Commits
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1e88b9d Fix "versionadded" position
8cfb850 [Reference][Form Types] Document "with_minutes" time/datetime option
[Contributing] Clarify the rebase operation

I just mentioned the fact that `push -f` is usually required when rebasing and explicit that the "2.2 when bugfixing" is a follow up on the previous example (Not necessarily explicit at first).
[Contributing] Fix single vs double backtick issues
[Contributing] Add PSR-1 and 2 links
[Contributing] Replace mentions of 2.2 for 2.3

As per WouterJ request: https://github.com/symfony/symfony-docs/pull/3421#issuecomment-31585092
[Contributing] Fix "When you finish" => "When you are finished"

As per @xabbuh suggestion: https://github.com/symfony/symfony-docs/pull/3421#discussion_r8661716
[Contributing] Replace HEAD~3 by upstream/master

As per @cordoval suggestion: https://github.com/symfony/symfony-docs/pull/3421#discussion_r8670868
Merge branch '2.3' into 2.4