Standardize sliding numbers

[Managor]

Currently we are mostly going with the idea that when number is explicitly stated in the description, it is not marked as a placeholder, but there seems to be disagreement on what is best here. See #16405 (comment)

Personally I feel like sliding numbers like disk sizes could be marked as a placeholder but I'm asking for opinions.

cc. @sebastiaanspeck

[sebastiaanspeck]

IMO opinion it is depend on the description of the example;

- … specific size:

… {{10}}

OR

- … 10 GB:

… 10

It should become clear in one of the two what the expected notation needs to be.