docs: use uppercase entropy symbol H in C example output

Author: Planeshifter

lib/node_modules/@stdlib/stats/base/dists/poisson/entropy/README.md

@@ -192,7 +192,7 @@ int main( void ) {
     for ( i = 0; i < 25; i++ ) {
         lambda = random_uniform( 0.0, 20.0 );
         y = stdlib_base_dists_poisson_entropy( lambda );
-        printf( "λ: %lf, h(X;λ): %lf\n", lambda, y );
+        printf( "λ: %lf, H(X;λ): %lf\n", lambda, y );
     }
 }
 ```

lib/node_modules/@stdlib/stats/base/dists/poisson/entropy/examples/c/example.c

@@ -33,6 +33,6 @@ int main( void ) {
 	for ( i = 0; i < 25; i++ ) {
 		lambda = random_uniform( 0.0, 20.0 );
 		y = stdlib_base_dists_poisson_entropy( lambda );
-		printf( "λ: %lf, h(X;λ): %lf\n", lambda, y );
+		printf( "λ: %lf, H(X;λ): %lf\n", lambda, y );
 	}
 }