refs #24469 [finc] composer docker: add description in .env file

.env.local

@@ -3,8 +3,8 @@ GRUNT_SASS=^3.1.0
 JIT_GRUNT=^0.10.0
 NODE_SASS=^7.0.1
 
-# Dependencies for composer task (loads files for vendor)
+# Dependencies for composer task (loads files for vendor): composer1 | composer2
 COMPOSER_VERSION=composer2
 
-# Version for php in PHP container
+# Version for php in PHP container: php7_2 | php8_0
 PHP_VERSION=php7_2
\ No newline at end of file