add requested suggestions

Author: shubham220420

lib/node_modules/@stdlib/stats/base/dists/halfnormal/variance/README.md

@@ -178,7 +178,6 @@ double out = stdlib_base_dists_halfnormal_variance( 1.0 );
 The function accepts the following arguments:
 
 -   **sigma**: `[in] double` scale parameter.
--   **return**: `[out] double` variance.
 
 ```c
 double stdlib_base_dists_halfnormal_variance( const double sigma );

lib/node_modules/@stdlib/stats/base/dists/halfnormal/variance/test/test.native.js

@@ -52,18 +52,18 @@ tape( 'main export is a function', opts, function test( t ) {
 
 tape( 'if provided `NaN`, the function returns `NaN`', opts, function test( t ) {
 	var y = variance( NaN );
-	t.strictEqual( isnan( y ), true, 'returns NaN' );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
 	t.end();
 });
 
 tape( 'if provided a nonpositive `sigma`, the function returns `NaN`', opts, function test( t ) {
 	var y;
 
 	y = variance( 0.0 );
-	t.strictEqual( isnan( y ), true, 'returns NaN' );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
 
 	y = variance( -1.0 );
-	t.strictEqual( isnan( y ), true, 'returns NaN' );
+	t.strictEqual( isnan( y ), true, 'returns expected value' );
 
 	y = variance( NINF );
 	t.strictEqual( isnan( y ), true, 'returns expected value' );