Bookmark examples

Examples written in answer to questions such as:

• How to read bookmark titles?

fetchbookmarktitles:

##GITHUB:https://github.com/itext/i7js-examples/blob/develop/src/main/java/com/itextpdf/samples/sandbox/interactive/FetchBookmarkTitles.java##

##GITHUB:https://github.com/itext/i7ns-samples/blob/develop/itext/itext.samples/itext/samples/sandbox/interactive/FetchBookmarkTitles.cs##

changebookmarks

##GITHUB:https://github.com/itext/i7js-examples/blob/develop/src/main/java/com/itextpdf/samples/sandbox/stamper/ChangeBookmarks.java##

##GITHUB:https://github.com/itext/i7ns-samples/blob/develop/itext/itext.samples/itext/samples/sandbox/stamper/ChangeBookmarks.cs##