docs: fix type

Signed-off-by: Athan <kgryte@gmail.com>

Author: kgryte

lib/node_modules/@stdlib/blas/ext/base/gjoin/docs/repl.txt

@@ -16,7 +16,7 @@
     N: integer
         Number of indexed elements.
 
-    separator: any
+    separator: string
         Separator.
 
     x: Array|TypedArray