Fixed some typos and little tweaks

[perseoGI]

While reviewing docs for the conan training, I found some things that can be improved.

[memsharded]

Looks good overall, just a detail about per-package env

[memsharded]

This would be introducing here the concept of per-package environment, but this section is to introduce the core syntax (add, append, remove).

It would be better to leave it as-is, and then add the per-package examples with mypkg/* separately

[perseoGI]

I agree with you. There were two options, modifying this line or the below line.
See this screen capture from https://docs.conan.io/2/reference/config_files/profiles.html#profiles

I was confused about reading MyPath=! and then the explanation below.

That is why I added that pattern, because if not, the Unix/Windows explanation below will be invalidated, as after parsing all the profile, MyPath1 will be empty.

[memsharded]

Oh, that is wrong, indeed.
Lets try to improve it:

• Use MyPath2=! in the text
• Explain in the explanation that if the system had defined MyPath2, it will be unset by Conan
• After this example explanation, add a small example with per-package environment, a simple MyVar1=value1 followed by mypkg/*:MyVar1=value2 and explaining the final values would be enough

[perseoGI]

Updated: