Remove some "is"es from previous json checkin

* lisp/subr.el (json-available-p):
* doc/lispref/text.texi (Parsing JSON): Fix typo in last check-in.

doc/lispref/text.texi

@@ -5302,7 +5302,7 @@ represents @code{@{@}}, the empty JSON object; not @code{null},
 values.
 
 @defun json-available-p
-This predicate returns non-@code{nil} is Emacs has been built with
+This predicate returns non-@code{nil} if Emacs has been built with
 @acronym{JSON} support, and the library is available on the current
 system.
 @end defun

lisp/subr.el

@@ -6312,7 +6312,7 @@ This is intended for internal use only."
   (internal--fill-string-single-line (apply #'format string objects)))
 
 (defun json-available-p ()
-  "Return non-nil if Emacs is has libjansson support."
+  "Return non-nil if Emacs has libjansson support."
   (and (fboundp 'json-serialize)
        (condition-case nil
            (json-serialize t)