Mention the WebAssembly wrapper.

Change-Id: I658a4411055b717af024d774af5c93acf759cfa7
Reviewed-on: https://code-review.googlesource.com/c/re2/+/58330
Reviewed-by: Paul Wankadia <junyer@google.com>
diff --git a/README b/README
index 1187cbe..0e1142c 100644
--- a/README
+++ b/README
@@ -38,3 +38,4 @@
 A Perl wrapper is at https://github.com/dgl/re-engine-RE2/ and on CPAN (cpan.org).
 An R wrapper is at https://github.com/qinwf/re2r/ and on CRAN (cran.r-project.org).
 A Ruby wrapper is at https://github.com/mudge/re2/ and on RubyGems (rubygems.org).
+A WebAssembly wrapper is at https://github.com/google/re2-wasm/ and on NPM (npmjs.com).