[doc] Inconsistent documentation of \G

[djerius]

Where
perlre, perlretut

Description

perlretut warns that

Currently, the \G anchor is only fully supported when used to anchor to the start of the pattern.

whlie perlre provides an example showing \G being used at the end of a pattern:

while ($string =~ /(.\G)/g) {
    print $1;
}

without a similar warning.

There's no description of what not "fully supported" entails, and the example in perlre unaccompanied by a similar warning implies that it is fully supported.