Updated the README to include the C API documentation

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Author: anandkaranubc

lib/node_modules/@stdlib/stats/base/dists/arcsine/mean/README.md

@@ -133,6 +133,104 @@ for ( i = 0; i < 10; i++ ) {
 
 <!-- /.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/stats/base/dists/arcsine/mean.h"
+```
+
+#### stdlib_base_dists_arcsine_mean( a, b )
+
+Returns the expected value (mean) of an arcsine distribution.
+
+```c
+double out = stdlib_base_dists_arcsine_mean( 4.0, 12.0 );
+// returns 8.0
+```
+
+The function accepts the following arguments:
+
+-   **a**: `[in] double` minimum support.
+-   **b**: `[in] double` maximum support.
+
+```c
+double stdlib_base_dists_arcsine_mean( const double a, const double b );
+```
+
+</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">
+
+### Examples
+
+```c
+#include "stdlib/stats/base/dists/arcsine/mean.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+static double random_uniform( const double min, const double max ) {
+    double v = (double)rand() / ( (double)RAND_MAX + 1.0 );
+    return min + ( v * ( max - min ) );
+}
+
+int main( void ) {
+    double a;
+    double b;
+    double m;
+    int i;
+
+    for ( i = 0; i < 10; i++ ) {
+        a = random_uniform( -20.0, 0.0 );
+        b = random_uniform( a, a + 40.0 );
+        m = stdlib_base_dists_arcsine_mean( a, b );
+
+        printf( "a: %lf, b: %lf, Mean: %lf\n", a, b, m );
+    }
+
+    return 0;
+}
+```
+
+</section>
+
+<!-- /.examples -->
+
+</section>
+
+<!-- /.c -->
+
 <!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->
 
 <section class="references">