4-17 Unknown Tagged Literals: Add a See Also item

It took me a long time to figure out why clojure.edn/read didn't heed
data_readers.clj. (Because it's not supposed to.) Looking for answers,
recipe 4-17 turned up quite high in the search results, but didn't help
me much. When I finally figured it out, I hit my head against the wall
and suspected that other people have the same problems. So I added a
note to the ClojureDocs entry for clojure.edn/read.

Add a link to the ClojureDocs entry to the See Also section of recipe
4-17, so that people finding this recipe first, can achieve
enlightenment more quickly.

Author: rmoehn

04_local-io/4-17_unknown-reader-literals.asciidoc

@@ -137,6 +137,11 @@ for reading data, it's generally better to use the edn variants.footnote:[The Cl
 
 * https://github.com/edn-format/edn[edn: extensible data notation] on GitHub
 * <<sec_local_io_clojure_data_to_disk>>, and <<sec_edn_record>>
+* The entry for 
+  https://clojuredocs.org/clojure.edn/read[+clojure.edn/read+ on 
+  ClojureDocs] for a discussion about how the +clojure.core+ and
+  +clojure.edn+ reader procedures differ with regard to
+  +data_readers.clj+.
 
 ++++
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