Add hello world to samples page

assets/zig-code/samples/hello-world.zig

@@ -0,0 +1,9 @@
+const std = @import("std");
+const stdout = std.io.getStdOut().writer();
+
+pub fn main() !void {
+   try stdout.print("hello world!\n", .{});
+}
+
+// exe=succeed
+

content/en-US/learn/samples.smd

@@ -9,35 +9,40 @@
 },
 ---
 
+# [Hello world]($heading.id('ext'))
+A minimal example printing hello world.
+
+[]($code.language('=html').buildAsset("samples/hello-world.zig"))
+
 # [Calling external library functions]($heading.id('ext'))
 All system API functions can be invoked this way, you do not need library bindings to interface them.
 
-[]($code.language('=html').buildAsset("samples/0-windows-msgbox.zig"))
+[]($code.language('=html').buildAsset("samples/windows-msgbox.zig"))
 
 # [Memory leak detection]($heading.id('leak'))
 Using `std.heap.GeneralPurposeAllocator` you can track double frees and memory leaks.
 
-[]($code.language('=html').buildAsset("samples/1-memory-leak.zig"))
+[]($code.language('=html').buildAsset("samples/memory-leak.zig"))
 
 
 # [C interoperability]($heading.id('c-interop'))
 Example of importing a C header file and linking to both libc and raylib.
 
-[]($code.language('=html').buildAsset("samples/2-c-interop.zig"))
+[]($code.language('=html').buildAsset("samples/c-interop.zig"))
 
 
 # [Zigg Zagg]($heading.id('zigg-zagg'))
 Zig is *optimized* for coding interviews (not really).
 
-[]($code.language('=html').buildAsset("samples/3-ziggzagg.zig"))
+[]($code.language('=html').buildAsset("samples/ziggzagg.zig"))
 
 
 # [Generic Types]($heading.id('generic'))
 In Zig types are comptime values and we use functions that return a type to implement generic algorithms and data structures. In this example we implement a simple generic queue and test its behaviour.
 
-[]($code.language('=html').buildAsset("samples/4-generic-type.zig"))
+[]($code.language('=html').buildAsset("samples/generic-type.zig"))
 
 
 # [Using cURL from Zig]($heading.id('curl'))
 
-[]($code.language('=html').buildAsset("samples/5-curl.zig"))
+[]($code.language('=html').buildAsset("samples/curl.zig"))