I've never heard of such a thing and would be incredibly surprised to hear of such a thing existing. Islamists, like all pious Muslims, hold the Quran to be the Word of God-- perfect, complete and inviolable.

my theory that ISIS does not truely represent the Islamic religion

I don't want to get into 20 year rule issues, but to argue that violent Islamists do not "truly represent the Islamic religion" is a bit of a red herring. There is very little in the doctrines of such groups that they do not attempt to base in the texts and doctrines of the religion itself, even if the result is a perversion of what most Muslims regard as being core tenets of their own faith (like not killing yourself, or killing civilians.)

Arguments about "true Islam" by what is clearly a very large portion of that faith are not especially fruitful.

A select group of Islamist militants formed indoctrination camps

This is true enough, although it wasn't especially select. The Pakistani government with the support of Saudi Arabia, international organizations of the Muslim Brotherhood, and others (including, ultimately, funds that came from the US and were given to Pakistan) set up hardline religious madrassas on the Pakistani border for Afghan refugees with an eye to diverting these young men into Jihad and to supporting Pakistan's particular brand of Islamic government.

The connection between these camps/schools and later transnational terrorist movements is not so simple, however. While many of these young men would later join and support the Taliban, they were not necessarily involved in the founding of Al-Qaeda or in the formation of the doctrines of an internationalist and anti-western Jihadist movement. Moreover, the Arabs who were involved in the Afghan Jihad (e.g. Osama bin Laden) arguably received the least amount of attention and support from official channels because it was assumed that they were self funded, self motivated, and they were not regarded as being very effective. These schools were not intended for them, and they were in large part being indoctrinated and recruited by elements of the international Muslim Brotherhood organization, or individuals affiliated to it like Abdullah Azzam.

There's also quite a lot we can point to prior to the Soviet invasion and the establishment of these Madrassas that would be pretty important for understanding the foundations and doctrines of violent Islamism-- such as the publication of Sayyid Qutb's writings. Or that were just completely unrelated to what was going in Afghanistan, such as the establishment of Hezbollah (initially underground and pseudonymously referred to as the "Islamic Jihad Organization") and their pioneering of massive suicide bomb attacks.