Add hint for percent escape in translatable values

[Dahesor]

In the above situation, the % is just a part of the text. This is accepted by the game, but Spyglass marks it as an error and expects a following s.

[SPGoding]

Percent signs in translatable text should be escaped by using %% instead of %. The fact that the game does not complain loudly about the use of a single % does not mean it's good practice (as something like You have a %s % chance would not work -- the first %s would not be treated as a placeholder by the game. I suspect the game just gives up on formatting correctly when it encounters a single %), and in general we tend to be stricter than the game itself in our checking to encourage good practice and avoid common pitfalls.

I think one potential improvement we could make is to update the error message to mention the fact that literal percent signs should be escaped as %% though.