Merge pull request #253 from ljharb/update_readme

Using source instead of dot. Closes #211.

README.markdown

@@ -27,7 +27,7 @@ Or if you have `git` installed, then just clone it:
 
 To activate nvm, you need to source it from your bash shell
 
-    . ~/.nvm/nvm.sh
+    source ~/.nvm/nvm.sh
 
 I always add this line to my `~/.bashrc` or `~/.profile` file to have it automatically sourced upon login.   
 Often I also put in a line to use a specific version of node.