Document that comments aren't preserved for round trip (apache#1060)

Author: takluyver

README.md

@@ -61,12 +61,12 @@ analysis, feel free to use this project as a base.
 
 ## Preserves Syntax Round Trip 
 
-This crate allows users to recover the original SQL text (with normalized
-whitespace and keyword capitalization), which is useful for tools that
-analyze and manipulate SQL.
+This crate allows users to recover the original SQL text (with comments removed,
+normalized whitespace and keyword capitalization), which is useful for tools
+that analyze and manipulate SQL.
 
-This means that other than whitespace and the capitalization of keywords, the
-following should hold true for all SQL:
+This means that other than comments, whitespace and the capitalization of
+keywords, the following should hold true for all SQL:
 
 ```rust
 // Parse SQL

src/lib.rs

@@ -41,9 +41,9 @@
 //!
 //! # Creating SQL text from AST
 //!
-//! This crate allows users to recover the original SQL text (with normalized
-//! whitespace and identifier capitalization), which is useful for tools that
-//! analyze and manipulate SQL.
+//! This crate allows users to recover the original SQL text (with comments
+//! removed, normalized whitespace and identifier capitalization), which is
+//! useful for tools that analyze and manipulate SQL.
 //!
 //! ```
 //! # use sqlparser::dialect::GenericDialect;