Incorrect description of possible coercions for method receivers

[afetisov]

In the list of coercions, it is claimed in the section of function arguments

For method calls, the receiver (self parameter) can only take advantage of unsized coercions.

But this isn't true, the deref coercions are also applied to the method receiver. The transitive and subtyping coercions are also applied, and there may be some other cases.