package/chicken: fix references to libchicken

While applying, the package was renamed from libchicken to chicken, but
two references remained: in DEVELOPERS, and in the Config.in help text.
Fix both.

While we're at it, extend the help text by copying the first sentence of
the website.

Signed-off-by: Arnout Vandecappelle <arnout@mind.be>

DEVELOPERS

@@ -3282,7 +3282,7 @@ N:	Wojciech Niziński <niziak@spox.org>
 F:	package/fwup/
 
 N:	Woodrow Douglass <wdouglass@carnegierobotics.com>
-F:	package/libchicken
+F:	package/chicken
 F:	package/opencv4
 F:	package/opencv4-contrib
 

package/chicken/Config.in

@@ -2,6 +2,8 @@ config BR2_PACKAGE_CHICKEN
 	bool "chicken"
 	depends on BR2_USE_MMU
 	help
-	  libchicken is the runtime library for chicken scheme.
+	  CHICKEN is a compiler for the Scheme programming language.
+	  This package contains the runtime, the interpreter, and
+	  the (native for target) compiler.
 
 	  https://call-cc.org