Fix README typos and clarify

[stephen-soltesz]

These changes fix two typos and clarifying language reported by a user.

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 941

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 80.282%

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Totals
Change from base Build 939:	0.0%
Covered Lines:	1083
Relevant Lines:	1349

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💛 - Coveralls

[SaiedKazemi]

cmd/csvtool/README.md line 6 at r1 (raw file):

tcp-info to more easily usable CSV files. csvtool currently only handles
individual, raw or zstd compressed JSONL files as a source.  Named files should
be the only parameter. If reading uncompressed JSONL from STDIN, provide no

nit: can we use stdin here like it's written elsewhere (and also how typically written)?

[SaiedKazemi]

[SaiedKazemi]

Reviewed 2 of 2 files at r1, all commit messages.
Reviewable status: complete! 1 of 1 LGTMs obtained