Had been stepping into Bukkit API development for a few months, most of the time I use the spigot website (https://hub.spigotmc.org/javadocs/bukkit/) to check for the APIs, last month when 1.11 released, the documentation was updated to v1.11 as well.
Due to not wanting to update the code to 1.11 at the current moment, where can I find the API documentation for Bukkit v1.10.2?
While I'm not aware of a site that contains the documentation for a previous version, the Maven repo for spigot does have source and documentation jars for each version that you should be able to attach to in your IDE.
If you want to manually set it up (or Maven refuses to work), you can manually find the jars here - first select your version, and then download the latest -javadoc.jar (which will be at the bottom of the page). You can unzip that jar (which contains HTML pages rather than source or classes) and then you'll have a copy of the javadocs from that version. In the case of 1.10.2, the jar you want is this one.