Merge 1fe56af526 into 236ba5690e

Add more documentation for the --build-arg parameter of the executor.
Describe that it's possible to lookup build argument values from the
environment and that this might be useful if you don't want to fiddle
around with shell escaping.

MAINTAINERS

@@ -1,2 +0,0 @@
-Jerome Ju <jeromeju@google.com>
-Quan Zhang <zhangquan@google.com>

README.md

@@ -1,3 +1,11 @@
+# 🧊 This project is archived and no longer developed or maintained. 🧊
+
+The code remains available for historic purposes.
+
+The README as of the archival date remains unchanged below for historic purposes.
+
+-----
+
 # kaniko - Build Images In Kubernetes
 
 ## 🚨NOTE: kaniko is not an officially supported Google product🚨
@@ -806,6 +814,18 @@ export IFS=''
 /kaniko/executor --build-arg "MY_VAR='value with spaces'" ...
 ```
 
+It is also possible to lookup the build argument value from the environment
+variables which is especially useful when you already have the build argument
+value in the environment variables and don't want to fiddle around with shell escaping.
+To use an environment variable as build argument value, you just need to
+use the `--build-arg` parameter just with the name of the argument:
+
+```bash
+/kaniko/executor --build-arg "MY_VAR" ...
+```
+In this example, Kaniko will then set the build argument `MY_VAR` to the value of the environment
+variable `MY_VAR`.
+
 #### Flag `--cache`
 
 Set this flag as `--cache=true` to opt into caching with kaniko.