Document how to reload nvm after upgrading

README.markdown

@@ -61,6 +61,10 @@ For manual upgrade with `git`, change to the `$NVM_DIR`, pull down the latest ch
 
     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
 
 You can create an `.nvmrc` file containing version number in the project root directory (or any parent directory).