Update OSC section on "Console Virtual Terminal Sequences" to include updated string terminators

[zadjii-msft]

In ColorTool I see we use BEL as OSC end. I believe it aligns with xterm.
string s = $"\x1b]4;{vtIndex};rgb:{color.R:X}/{color.G:X}/{color.B:X}\x7"
https://github.com/microsoft/terminal/blob/master/src/tools/ColorTool/ColorTool/ConsoleTargets/VirtualTerminalConsoleTarget.cs
but in the doc, it says ESC as end
I think it wants to say "ESC ", which is ST

We should make sure specifically the string terminators for the OSC section get updated.

(subset of #91)

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Document Details

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• ID: fc536527-f75d-5a03-7b5a-338a08e40d2f
• Version Independent ID: 097f43d9-243f-466e-1f99-6cfa1f4bfb1f
• Content: Console Virtual Terminal Sequences - Windows Console
• Content Source: docs/console-virtual-terminal-sequences.md
• Product: console
• GitHub Login: @bitcrazed
• Microsoft Alias: richturn

[bef178]

Typo:

I think it wants to say "ESC \", which is ST

[miniksa]

This could be cross-referenced by anyone against the code in the Microsoft/Terminal repo.

[KalleOlaviNiemitalo]

bool _isOscTerminator(wchar_t) supports either BEL or single-character (U+009C) ST as the terminator after OSC.

bool _isOscTerminationInitiator(wchar_t) recognizes the first character of the two-character (ESC 0x5C) representation of ST, and void StateMachine::_EventOscTermination(wchar_t) then behaves as if the second character were 0x5C but does not check.