fix: edit function name in readme

Author: 0PrashantYadav0

lib/node_modules/@stdlib/stats/base/dists/exponential/pdf/README.md

@@ -172,7 +172,7 @@ The function accepts the following arguments:
 -   **lambda**: `[in] double` rate parameter.
 
 ```c
-double stdlib_base_dists_uniform_mgf( const double x, const double lambda );
+double stdlib_base_dists_exponential_pdf( const double x, const double lambda );
 ```
 
 </section>