docs: fix incorrect return value in C usage section weibull/logpdf

PR-URL: #10956

Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>

Author: Om-A-osc

lib/node_modules/@stdlib/stats/base/dists/weibull/logpdf/README.md

@@ -183,7 +183,7 @@ Evaluates the logarithm of the [probability density function][pdf] (PDF) for a [
 
 ```c
 double out = stdlib_base_dists_weibull_logpdf( 2.0, 1.0, 0.5 );
-// returns ~3.307
+// returns ~-3.307
 ```
 
 The function accepts the following arguments: