docs: Edit rustc_span::symbol::Symbol method
docs: Edit rustc_span::symbol::Symbol method

Edit wording of the doc comment for rustc_span::symbol::Symbol::can_be_raw
to match related methods.
aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust