Document how to reload nvm after upgrading

README.markdown

@@ -60,6 +60,10 @@ Add these lines to your `~/.bashrc`, `~/.profile`, or `~/.zshrc` file to have it
 For manual upgrade with `git`, change to the `$NVM_DIR`, pull down the latest changes, and check out the latest version:
 
     cd "$NVM_DIR" && git pull origin master && git checkout `git describe --abbrev=0 --tags`
+    
+After upgrading, don't forget to activate the new version:
+
+    . "$NVM_DIR/nvm.sh"
 
 ## Usage