Better string docs

pkg/yqlib/doc/operators/headers/string-operators.md

@@ -3,6 +3,17 @@
 ## RegEx
 This uses golangs native regex functions under the hood - See https://github.com/google/re2/wiki/Syntax for the supported syntax.
 
+### match(regEx)
+This operator returns the substring match details of the given regEx.
+
+### capture(regEx)
+Capture returns named RegEx capture groups in a map. Can be more convenient than `match` depending on what you are doing.
+
+# test(regEx)
+Returns true if the string matches the RegEx, false otherwise.
+
+## sub(regEx, replacement)
+Substitutes matched substrings. The first parameter is the regEx to match substrings within the original string. The second is a what to replace those matches with. This can refer to capture groups from the first RegEx.
 
 ## String blocks, bash and newlines
 Bash is notorious for chomping on precious trailing newline characters, making it tricky to set strings with newlines properly. In particular, the `$( exp )` _will trim trailing newlines_.

pkg/yqlib/doc/operators/string-operators.md

@@ -3,6 +3,17 @@
 ## RegEx
 This uses golangs native regex functions under the hood - See https://github.com/google/re2/wiki/Syntax for the supported syntax.
 
+### match(regEx)
+This operator returns the substring match details of the given regEx.
+
+### capture(regEx)
+Capture returns named RegEx capture groups in a map. Can be more convenient than `match` depending on what you are doing.
+
+# test(regEx)
+Returns true if the string matches the RegEx, false otherwise.
+
+## sub(regEx, replacement)
+Substitutes matched substrings. The first parameter is the regEx to match substrings within the original string. The second is a what to replace those matches with. This can refer to capture groups from the first RegEx.
 
 ## String blocks, bash and newlines
 Bash is notorious for chomping on precious trailing newline characters, making it tricky to set strings with newlines properly. In particular, the `$( exp )` _will trim trailing newlines_.