revert: restore N <= 0 boundary condition in stats/strided/distances/dcorrelation REPL help

Per maintainer review: the explicit guard in the implementation is `N <= 0`, so the REPL help should match.

https://claude.ai/code/session_01PYMuhnRSCirT5T3Bn4o4Lj

Author: claude

lib/node_modules/@stdlib/stats/strided/distances/dcorrelation/docs/repl.txt

@@ -9,7 +9,7 @@
     Indexing is relative to the first index. To introduce an offset, use a typed
     array view.
 
-    If `N <= 1`, the function returns `NaN`.
+    If `N <= 0`, the function returns `NaN`.
 
     Parameters
     ----------