add better documentation to `--filter`

[georgettica]

related to

cli-ux/src/styled/table.ts

Line 320 in 4e5c19b

filter: F.string({description: 'filter property by partial string matching, ex: name=foo'}),

after reading

cli-ux/src/styled/table.ts

Lines 64 to 77 in fd0ca55

	if (this.options.filter) {
	/* eslint-disable-next-line prefer-const */
	let [header, regex] = this.options.filter!.split('=')
	const isNot = header[0] === '-'
	if (isNot) header = header.substr(1)
	const col = this.findColumnFromHeader(header)
	if (!col || !regex) throw new Error('Filter flag has an invalid value')
	rows = rows.filter((d: any) => {
	const re = new RegExp(regex)
	const val = d[col!.key]
	const match = val.match(re)
	return isNot ? !match : match
	})
	}

I was able to deduce the != doesn't exist in the query language and a prepended - will do the trick

this could have been subverted if the help message would direct me to documentation on how the filter query language works

[georgettica]

@RodEsp @mattgraham could I get your 2 cents before giving it a go?

[RodEsp]

Hey @georgettica, thanks for pointing this out!
You're right that the --filter flag doesn't support the != operator which is confusing.

If you'd just like to update the docs that would be wonderful but feel free to also take a shot at adding support for that operator if you'd like.

[georgettica]

created a PR with some related changes
#435
also, as this is hacktobefest.. can this PR be included in it?
if not it's fine

[georgettica]

Did you see my second solution to the problem?

I understand that this is not exactly what you expected, but maybe you will see the additional features it provides

[georgettica]

@RodEsp I created a different PR to solve the issue

There is still code-changes and it's not perfect, but closer?
If not I'll add a PR with only doc changes and maybe a markdown with the query structure
#447