Document that we support srfi-62 and add it to %cond-expand-features.

* module/ice-9/boot-9.scm (%cond-expand-features): Add srfi-62.

* doc/ref/srfi-modules.texi (SRFI-0): Add srfi-62 to the list of core
  features.
  (SRFI-62): New node.

doc/ref/srfi-modules.texi

@@ -51,6 +51,7 @@ get the relevant SRFI documents from the SRFI home page
 * SRFI-55::                     Requiring Features.
 * SRFI-60::                     Integers as bits.
 * SRFI-61::                     A more general `cond' clause
+* SRFI-62::                     S-expression comments.
 * SRFI-67::                     Compare procedures
 * SRFI-69::                     Basic hash tables.
 * SRFI-88::                     Keyword objects.
@@ -154,6 +155,7 @@ srfi-30
 srfi-39
 srfi-55
 srfi-61
+srfi-62
 srfi-105
 @end example
 
@@ -4836,6 +4838,13 @@ success.  SRFI 61 is implemented in the Guile core; there's no module
 needed to get SRFI-61 itself.  Extended @code{cond} is documented in
 @ref{Conditionals,, Simple Conditional Evaluation}.
 
+@node SRFI-62
+@subsection SRFI-62 - S-expression comments.
+@cindex SRFI-62
+
+Starting from version 2.0, Guile's @code{read} supports SRFI-62/R7RS
+S-expression comments by default.
+
 @node SRFI-67
 @subsection SRFI-67 - Compare procedures
 @cindex SRFI-67

module/ice-9/boot-9.scm

@@ -4043,6 +4043,7 @@ when none is available, reading FILE-NAME with READER."
     srfi-39  ;; parameterize
     srfi-55  ;; require-extension
     srfi-61  ;; general cond clause
+    srfi-62  ;; s-expression comments
     srfi-105 ;; curly infix expressions
     ))