I too interpretat those docs as contradictory, and I wonder if, like how Java 5 strengthened volatile semantics, this happened at some point in C# too and the docs weren't updated? Either way the specification, which the docs say is definitive, says it's acquire/release.
"When a field_declaration includes a volatile modifier, the fields introduced by that declaration are volatile fields. [...] For volatile fields, such reordering optimizations are restricted:
A read of a volatile field is called a volatile read. A volatile read has “acquire semantics”; that is, it is guaranteed to occur prior to any references to memory that occur after it in the instruction sequence.
A write of a volatile field is called a volatile write. A volatile write has “release semantics”; that is, it is guaranteed to happen after any memory references prior to the write instruction in the instruction sequence."
https://learn.microsoft.com/en-us/dotnet/csharp/language-ref...
"When a field_declaration includes a volatile modifier, the fields introduced by that declaration are volatile fields. [...] For volatile fields, such reordering optimizations are restricted: