doc: update file keywords v2

[jmtaylor90]

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Describe changes:

• Update file.magic and file.name keyword information to reflect recent updates
• Update libmagic dependency information and reference
• Address comments in doc: update file keywords v1 #9245

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[jufajardini]

Seems to me that this has addressed Victor's comments from previous PR.
Wondering a bit if we should reword where it's stated that the only difference between legacy and new keywords is the nocase, since the keyword syntax seems to be slightly different...

[jmtaylor90]

Seems to me that this has addressed Victor's comments from previous PR. Wondering a bit if we should reword where it's stated that the only difference between legacy and new keywords is the nocase, since the keyword syntax seems to be slightly different...

Sure, I will take another look at how those section(s) are worded.

[jmtaylor90]

continued in #9327