[Small PR] Added Notes to Glass DD6

[samm82]

And changed function names from using "t1" and "t2" to the more informative "pb" and "lr"

[smiths]

We discussed this recently in #914. I'm fine with the new names. However, we might want to revisit our variable naming in the future to carry a bit more information through stylistic conventions. For instance, we might later decide to add prefixes to variable names to give a quick mnemonic about their purpose, like T, D, I, etc. This would be like a modified Hungarian notation:

https://en.wikipedia.org/wiki/Hungarian_notation

[JacquesCarette]

Changes are fine, but there is now a conflict - can you fix please @samm82 ?

[samm82]

Done 👍