Precise the static path absolute path

.env.sample

@@ -75,7 +75,7 @@
 # Default: .pdf
 # BK_INSTRUCTIONS_ALLOWED_EXTENSIONS=.pdf, .docx, .png
 
-# Optional: Folder where to store the instructions, relative to the 'static/' folder
+# Optional: Folder where to store the instructions, relative to the '/app/static/' folder
 # Default: instructions
 # BK_INSTRUCTIONS_FOLDER=/var/lib/bricktracker/instructions/
 
@@ -122,7 +122,7 @@
 # Default: minifigures.name ASC
 # BK_MINIFIGURES_DEFAULT_ORDER=minifigures.name ASC
 
-# Optional: Folder where to store the minifigures images, relative to the 'static/' folder
+# Optional: Folder where to store the minifigures images, relative to the '/app/static/' folder
 # Default: minifigs
 # BK_MINIFIGURES_FOLDER=minifigures
 
@@ -141,7 +141,7 @@
 # Default: inventory.name ASC, inventory.color_name ASC, is_spare ASC
 # BK_PARTS_DEFAULT_ORDER=total_missing DESC, inventory.name ASC
 
-# Optional: Folder where to store the parts images, relative to the 'static/' folder
+# Optional: Folder where to store the parts images, relative to the '/app/static/' folder
 # Default: parts
 # BK_PARTS_FOLDER=parts
 
@@ -212,7 +212,7 @@
 # Default: set_number DESC, set_version ASC
 # BK_SETS_DEFAULT_ORDER=sets.year ASC
 
-# Optional: Folder where to store the sets images, relative to the 'static/' folder
+# Optional: Folder where to store the sets images, relative to the '/app/static/' folder
 # Default: sets
 # BK_SETS_FOLDER=sets