chore: add float32/pi link and definitions

Author: Neerajpathak07

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

@@ -20,7 +20,7 @@ limitations under the License.
 
 # FLOAT32_PI_SQUARED
 
-> π².
+> [π][@stdlib/constants/float32/pi]².
 
 <section class="usage">
 
@@ -32,7 +32,7 @@ var FLOAT32_PI_SQUARED = require( '@stdlib/constants/float32/pi-squared' );
 
 #### FLOAT32_PI_SQUARED
 
-Square of the mathematical constant π.
+Square of the mathematical constant [π][@stdlib/constants/float32/pi].
 
 ```javascript
 var bool = ( FLOAT32_PI_SQUARED === 9.869604110717773 );
@@ -90,7 +90,7 @@ console.log( FLOAT32_PI_SQUARED );
 
 #### STDLIB_CONSTANT_FLOAT32_PI_SQUARED
 
-Macro for the square of the mathematical constant π.
+Macro for the square of the mathematical constant [π][@stdlib/constants/float32/pi].
 
 </section>
 
@@ -128,6 +128,8 @@ Macro for the square of the mathematical constant π.
 
 <section class="links">
 
+[@stdlib/constants/float32/pi]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/constants/float32/pi
+
 </section>
 
 <!-- /.links -->