Clarify raw string literal multi-line rules for opening quotes and whitespace handling (#47728)

* Initial plan

* Clarify raw string literal multi-line rules for opening quotes and whitespace handling

Co-authored-by: BillWagner <[email protected]>

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Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: BillWagner <[email protected]>

Author: Copilot

docs/csharp/language-reference/tokens/raw-string.md

@@ -17,9 +17,9 @@ Raw string literals can span multiple lines:
 
 The following rules govern the interpretation of a multi-line raw string literal:
 
-- The opening quotes must be the last non-comment token on its respective line, and the closing quote must be the first non-comment token on its respective line.
+- The opening quotes must be the last non-whitespace characters on their line, and the closing quotes must be the first non-whitespace characters on their line.
 - Any whitespace to the left of the closing quotes is removed from all lines of the raw string literal.
-- Whitespace following the opening quote on the same line is ignored.
+- Any whitespace following the opening quotes on the same line is ignored.
 - Whitespace only lines following the opening quote are included in the string literal.
 - If a whitespace precedes the end delimiter on the same line, the exact number and kind of whitespace characters (for example, spaces vs. tabs) must exist at the beginning of each content line. Specifically, a space does not match a horizontal tab, and vice versa.
 - The newline before the closing quotes isn't included in the literal string.