Update Description field in DESCRIPTION file with comprehensive summary and paper citation

Co-authored-by: osorensen <21175639+osorensen@users.noreply.github.com>

Author: Copilot

DESCRIPTION

@@ -7,8 +7,13 @@ Authors@R: c(person("Oystein", "Sorensen",
                     role = c("aut", "cre"),
                     comment = c(ORCID = "0000-0003-0724-3542")))
 Maintainer: Oystein Sorensen <oystein.sorensen.1985@gmail.com>
-Description: Nested sequential Monte Carlo algorithms for the Bayesian Mallows
-    model.
+Description: Provides nested sequential Monte Carlo algorithms for performing
+    sequential inference in the Bayesian Mallows model, which is a widely used 
+    probability model for rank and preference data. The package implements the 
+    SMC² (Sequential Monte Carlo Squared) algorithm for handling sequentially 
+    arriving rankings and pairwise preferences, including support for complete 
+    rankings, partial rankings, and pairwise comparisons. The methods are based 
+    on Sørensen (2025) <doi:10.1214/25-BA1564>.
 License: GPL-3
 Encoding: UTF-8
 LazyData: true