Add more examples to README about regexp2

[dlclark]

The only time there will be multiple Captures in a Group is when the group repeats. For example: pattern ([0-9][A-Z])+ against the text 0A1B2C . Note the group itself repeats, so each repetition is stored in a separate Capture for that Group.

re := regexp2.MustCompile(`([0-9][A-Z])+`, 0)
m, _ := re.FindStringMatch(`0A1B2C`)
fmt.Printf("Group0:%v\n", m.String()) //0A1B2C
gps := m.Groups()
fmt.Printf("Cap0:%v\n", gps[1].Captures[0].String()) //0A
fmt.Printf("Cap1:%v\n", gps[1].Captures[1].String()) //1B
fmt.Printf("Cap2:%v\n", gps[1].Captures[2].String()) //2C

Since your example regex doesn't have a repeating group you actually need the next Match in the string.

I assume for your use case you're not sure how many pairs of values you'll get, so you would want to loop through the matches like this:

re := regexp2.MustCompile(`(\b\w+)=(.*?(?=\s\w+=|$))`, 0)
s := `timestamp=05/Dec/2018:14:39:41 -0500 foo=bar`
for m, _ := re.FindStringMatch(s); m != nil; m, _ = re.FindNextMatch(m) {
	fmt.Printf("Group 0: %v\n", m.String())
	gps := m.Groups()
	fmt.Println(gps[1].String())
}

If you have any questions or run into any other problems let me know.