docs: fix broken link to structured sources

We used the wrong spelling for both the object and the function. Link to
both, once in the description and once in the example code.

docs/markdown/Rust.md

@@ -30,7 +30,7 @@ This is an implementation detail of Meson, and is subject to change in the futur
 
 *Note* This feature was added in 0.62
 
-You can use a [[structured_source]] for this. Structured sources are a dictionary
+You can use a [[@structured_src]] for this. Structured sources are a dictionary
 mapping a string of the directory, to a source or list of sources.
 When using a structured source all inputs *must* be listed, as Meson may copy
 the sources from the source tree to the build tree.
@@ -44,7 +44,7 @@ build time (when necessary), to avoid reconfiguring when sources change.
 ```meson
 executable(
     'rust_exe',
-    structured_sources(
+    [[#structured_sources]](
         'main.rs',
         {
             'foo' : ['bar.rs', 'foo/lib.rs', generated_rs],