fix: Docker build and run were not working (#3081)

* fix: Use single quotes instead of backticks when specifying the environment variable that should be substituted for the envsubst command.
GitHub issue: #3079
Removed duplicate calls to envsubst.
Default nginx listen port is now 80.
Adde markdown documentation.

* fix: Fixed some typos and wording in markdown documentation.
GitHub issue: #3079

Co-authored-by: Joe Boccanfuso <joe.boccanfuso@radicalimaging.com>

platform/docs/docs/deployment/nginx--image-archive.md

@@ -1,5 +1,5 @@
 ---
-sidebar_position: 4
+sidebar_position: 5
 ---
 
 # Nginx + Image Archive