To get here you just clicked on a version number in the text. The version numbers help you track what’s happened to the text since you last checked in. If the number you see now is different than when you last checked the text is different.
Small changes are further back in the order. For instance, a small change to the very first version, 18.104.22.168 would be 22.214.171.124. A larger change might jump directly to 126.96.36.199. If the number appears at the top of a page with numbered subsections the header number will be telling you whether any sections have changed, removed, or added. You can then look at the sub-section numbers to figure out which ones were altered.