Modify unreachable cabal website links

[July541]

Hello,
This pr is about the modification of cabal docs as they have changed their links from stable to latest, the previous is not available, I made it correct.

[jneira]

@July541 many thanks for the correction
(btw you could had changed the previous pr with a force push and renaming it in github but open a new one it is fine too)

[jneira]

Just for being complete:

• urls were changed following the cabal issue: at cabal.readthedocs.io, show stable or all versions instead of redirecting to latest cabal#6966
• afaiu the disabling of stable urls is temporary and they will be restored
• we should return to stable urls as soon they are available
  • cause latest is (or could be) about the bleeding edge version not officially released

[July541]

@July541 many thanks for the correction
(btw you could had changed the previous pr with a force push and renaming it in github but open a new one it is fine too)

Thank you for your advice to a rookie!

[fendor]

Thank you!