style: align stats/base/dists/chisquare/entropy with namespace conventions

Added missing `chisq` keyword (present in 11/14 siblings, 79%). The
package already lists `chisquare`, `chisquared`, `chi-square`, and
`chi-squared`, so the short-form alias was the sole omission
relative to the majority pattern.

Author: claude

lib/node_modules/@stdlib/stats/base/dists/chisquare/entropy/package.json

@@ -62,6 +62,7 @@
     "shannon",
     "information",
     "nats",
+    "chisq",
     "chisquare",
     "chisquared",
     "chi-square",