Same content shared between multiple posts?

I want to have some cotent shared between various posts.

Why?

I am writing a series of posts on backbone js. The thing is every post has some common content ie from where you can download the source code etc. Now everytime I want to make a new post, I just copy paste that same content. Now one problem is: modifying the content. Today I want to modify the content in all the post. Now I have to manually edit the content in each post.

It will be great if I can use a shared copy something like partial in ruby on rails and just edit that shared copy and all the post having that shared copy get modified.

Any suggestions, plugins etc.