docs: add C API documentation for inv-two-pi constant

Author: Amansingh0807

lib/node_modules/@stdlib/constants/float32/inv-two-pi/README.md

@@ -60,6 +60,60 @@ console.log( FLOAT32_INV_TWO_PI );
 
 <!-- /.examples -->
 
+<!-- C interface documentation. -->
+
+* * *
+
+<section class="c">
+
+## C APIs
+
+<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->
+
+<section class="intro">
+
+</section>
+
+<!-- /.intro -->
+
+<!-- C usage documentation. -->
+
+<section class="usage">
+
+### Usage
+
+```c
+#include "stdlib/constants/float32/inv_two_pi.h"
+```
+
+#### STDLIB_CONSTANT_FLOAT32_INV_TWO_PI
+
+Macro for the inverse of twice the mathematical constant [π][pi] (1/(2π)).
+
+</section>
+
+<!-- /.usage -->
+
+<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
+
+<section class="notes">
+
+</section>
+
+<!-- /.notes -->
+
+<!-- C API usage examples. -->
+
+<section class="examples">
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
 <!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->
 
 <section class="related">