Update README.markdown

Talk about FreeBSD support.
Hope user can easily know that earlier, and also hope we can get much more help about this topic.

README.markdown

@@ -12,6 +12,10 @@ Note: `nvm` does not support [Fish] either (see [#303](https://github.com/creati
  - [nvm](https://github.com/derekstavis/plugin-nvm) plugin for [Oh My Fish](https://github.com/oh-my-fish/oh-my-fish), which makes nvm and its completions available in fish shell
  - [bass](https://github.com/edc/bass) allows to use utilities written for Bash in fish shell
 
+Note: We still have some problems with FreeBSD, because there is no pre-built binary from official for FreeBSD, and building from source may need [patches](https://www.freshports.org/www/node/files/patch-deps_v8_src_base_platform_platform-posix.cc), see the issue ticket:
+ - [[#900] [Bug] nodejs on FreeBSD need to be patched ](https://github.com/creationix/nvm/issues/900)
+ - [nodejs/node#3716](https://github.com/nodejs/node/issues/3716)
+
 ### Install script
 
 To install or update nvm, you can use the [install script][2] using cURL: