doc: add missing changes entry for breakEvalOnSigint REPL option

PR-URL: #35143
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

Author: addaleax

doc/api/repl.md

@@ -565,6 +565,9 @@ changes:
   - version: v10.0.0
     pr-url: https://github.com/nodejs/node/pull/19187
     description: The `REPL_MAGIC_MODE` `replMode` was removed.
+  - version: v6.3.0
+    pr-url: https://github.com/nodejs/node/pull/6635
+    description: The `breakEvalOnSigint` option is supported now.
   - version: v5.8.0
     pr-url: https://github.com/nodejs/node/pull/5388
     description: The `options` parameter is optional now.