docs: fix variable declarations

Author: kgryte

lib/node_modules/@stdlib/number/float32/base/to-binary-string/README.md

@@ -52,7 +52,7 @@ The function handles [subnormals][subnormals].
 ```javascript
 var toFloat32 = require( '@stdlib/number/float64/base/to-float32' );
 
-str = toBinaryStringf( toFloat32( -3.14e-39 ) );
+var str = toBinaryStringf( toFloat32( -3.14e-39 ) );
 // returns '10000000001000100011000100001011'
 
 str = toBinaryStringf( toFloat32( 1.4e-45 ) );
@@ -65,7 +65,7 @@ The function handles special values.
 var PINF = require( '@stdlib/constants/float32/pinf' );
 var NINF = require( '@stdlib/constants/float32/ninf' );
 
-str = toBinaryStringf( 0.0 );
+var str = toBinaryStringf( 0.0 );
 // returns '00000000000000000000000000000000'
 
 str = toBinaryStringf( -0.0 );