encoding/json: remove the word "text" in "JSON text" from package docs.

It was added in CL 79995. It is unnecessarily confusing.

Change-Id: Ib8ff35b9f71b54ff99d2d6e0534c7128e1f4345a
Reviewed-on: https://go-review.googlesource.com/80035Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/encoding/json/encode.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package json implements encoding and decoding of JSON text as defined in
+// Package json implements encoding and decoding of JSON as defined in
 // RFC 7159. The mapping between JSON and Go values is described
 // in the documentation for the Marshal and Unmarshal functions.
 //