finish build args section

docs/builds.md

@@ -23,7 +23,16 @@ Sometimes a command needs to be run before running ```docker build```, you can c
 
 There are two fields to pass for *pre build*. the first is *path*, which changes to working directory. To run the command in the root of the repo, just pass ```.```. The second field is *command*, this is the shell command to be executed after the repo is cloned.
 
-For example, say your repo had a folder in it called "scripts" with a shell script "on-clone.sh". You would give *path* as "scripts" and command as "sh on-clone.sh". Or you could make *path* just "." and then command would be "sh scripts/on-clone.sh". Either way works fine. 
+For example, say your repo had a folder in it called "scripts" with a shell script "on-clone.sh". You would give *path* as "scripts" and command as "sh on-clone.sh". Or you could make *path* just "." and then command would be "sh scripts/on-clone.sh". Either way works fine.
+
+## adding build args
+
+The Dockerfile may make use of [build args](https://docs.docker.com/engine/reference/builder/#arg). Build args can be passed using the gui by pressing the ```edit``` button. They are passed in the menu just like in a .env file:
+
+```
+BUILD_ARG1=some_value
+BUILD_ARG2=some_other_value
+```
 
 ## builder configuration