docs: updating singularity help build for sections to reflect order

docs/content.go

@@ -100,6 +100,9 @@ Enterprise Performance Computing (EPC)`
 
   DEFFILE SECTIONS:
 
+  The following sections are presented in the order of processing, with the exception
+  that labels and environment can also be manipulated in %post.
+
       %pre
           echo "This is a scriptlet that will be executed on the host, as root before"
           echo "the container has been bootstrapped. This section is not commonly used."
@@ -109,10 +112,20 @@ Enterprise Performance Computing (EPC)`
           echo "the container has been bootstrapped. To install things into the container"
           echo "reference the file system location with $SINGULARITY_ROOTFS."
 
+      %files
+          /path/on/host/file.txt /path/on/container/file.txt
+          relative_file.txt /path/on/container/relative_file.txt
+
       %post
           echo "This scriptlet section will be executed from within the container after"
           echo "the bootstrap/base has been created and setup."
 
+      %environment
+          LUKE=goodguy
+          VADER=badguy
+          HAN=someguy
+          export HAN VADER LUKE
+
       %test
           echo "Define any test commands that should be executed after container has been"
           echo "built. This scriptlet will be executed from within the running container"
@@ -131,16 +144,6 @@ Enterprise Performance Computing (EPC)`
           HELLO MOTO
           KEY VALUE
 
-      %files
-          /path/on/host/file.txt /path/on/container/file.txt
-          relative_file.txt /path/on/container/relative_file.txt
-
-      %environment
-          LUKE=goodguy
-          VADER=badguy
-          HAN=someguy
-          export HAN VADER LUKE
-
       %help
           This is a text file to be displayed with the run-help command.