docs: upstream buildah added some new fields and marked some as hidden

Signed-off-by: Aditya Rajan <arajan@redhat.com>

docs/source/markdown/podman-build.1.md

@@ -54,6 +54,10 @@ Add a custom host-to-IP mapping (host:ip)
 Add a line to /etc/hosts. The format is hostname:ip. The **--add-host** option
 can be set multiple times.
 
+#### **--all-platforms**=*value*
+
+Instead of building for a set of platforms specified using the **--platform** option, inspect the build's base images, and build for all of the platforms for which they are all available.  Stages that use *scratch* as a starting point can not be inspected, so at least one non-*scratch* stage must be present for detection to work usefully.
+
 #### **--annotation**=*annotation*
 
 Add an image *annotation* (e.g. annotation=*value*) to the image metadata. Can
@@ -117,6 +121,13 @@ given.
 Use certificates at *path* (\*.crt, \*.cert, \*.key) to connect to the registry. (Default: /etc/containers/certs.d)
 Please refer to containers-certs.d(5) for details. (This option is not available with the remote Podman client)
 
+#### **--cgroupns**=*namespace*
+
+Sets the configuration for cgroup namespaces when handling `RUN` instructions.
+The configured value can be "" (the empty string) or "private" to indicate
+that a new cgroup namespace should be created, or it can be "host" to indicate
+that the cgroup namespace in which `buildah` itself is being run should be reused.
+
 #### **--cgroup-parent**=*path*
 
 Path to cgroups under which the cgroup for the container will be created. If the
@@ -129,18 +140,6 @@ This option is added to be aligned with other containers CLIs.
 Podman doesn't communicate with a daemon or a remote server.
 Thus, compressing the data before sending it is irrelevant to Podman. (This option is not available with the remote Podman client)
 
-#### **--cni-config-dir**=*directory*
-
-Location of CNI configuration files which will dictate which plugins will be
-used to configure network interfaces and routing for containers created for
-handling `RUN` instructions, if those containers will be run in their own
-network namespaces, and networking is not disabled.
-
-#### **--cni-plugin-path**=*directory[:directory[:directory[...]]]*
-
-List of directories in which the CNI plugins which will be used for configuring
-network namespaces can be found.
-
 #### **--cpu-period**=*limit*
 
 Set the CPU period for the Completely Fair Scheduler (CFS), which is a
@@ -625,6 +624,10 @@ types include:
   "sigpending": maximum number of pending signals (ulimit -i)
   "stack": maximum stack size (ulimit -s)
 
+#### **--unsetenv**=*env*
+
+Unset environment variables from the final image.
+
 #### **--userns**=*how*
 
 Sets the configuration for user namespaces when handling `RUN` instructions.