fix: make save dir not having end-separator

[gabyx]

• the save dir should not have a end separator, IMO.
• corrected the readme too.

[MLFlexer]

Thanks for the PR!

1. Have you tested this locally?

2. Out of curiosity is it convention or useful in some way to not have the end-seperator?
   I am myself not aware of any reasons other than stylistic reasons, but maybe there is more to it?
   Either way, I would not mind merging this as I don't really have an opinion for when to have or not have the endning seperator in directories

[gabyx]

Its a convention.
And just weird. The PR does not work currently as there are more cases where you do some regex/sub or prefix removal which now does not work anymore.

[gabyx]

You can have the end separator internally, but I would not suggest, and make the API that it is agnostic to end separator ...

[MLFlexer]

Closing as it is not fixed, but opened #76 to eventually fix