New chapter page collecting the list of special variables

[NotTheDr01ds]

Added a "Special Variables" page to the "Nu Fundamentals" chapter. How many did I miss?

[132ikl]

you missed $env.PROCESS_PATH 😄

also, maybe it would be good to make a table of equivalent special variables in bash, perl, etc. for quick reference?

[NotTheDr01ds]

you missed $env.PROCESS_PATH 😄

Ah, yes - Thanks! I tested it and thought it had been removed, but I tested via source and use, but apparently not via script execution where it's valid.

also, maybe it would be good to make a table of equivalent special variables in bash, perl, etc. for quick reference?

Probably, but those tables are spread across several different pages today, and are starting to get (a) unwieldy and (b) outdated themselves. We also don't even have a Perl comparison today, but someone expressed interest in #1843. I'm not sure what the best way to handle it is.

[132ikl]

I think possibly adding a table to this page with a comparison of just the special variables possibly, and then link to that table from the other tables. It should be a much more compact table than the other tables

[132ikl]

thanks for taking care of this!

[kkoang]

Missing $env.NU_LOG_LEVEL
ref: Stdout, Stderr, and Exit Codes | Nushell

[Kissaki]

Missing $env.NU_LOG_LEVEL ref: Stdout, Stderr, and Exit Codes | Nushell

I created #1976