1. A computer program product for generating an appendix from document content comprising: a non-transitory computer readable storage medium, the document analytics system including program instructions executable by a processor, the program instructions comprising: program instructions to execute a zoning and structural analysis phase, wherein the zoning and structural analysis phase comprises program instructions to identify a document structure, and program instructions to store the identified document structure; in response to completing the zoning and structural analysis phase, program instructions to execute a semantic relationship extraction phase, wherein the semantic relationship extraction phase comprises program instructions to extract semantic relationships from the stored identified document structure, and program instructions to store the extracted semantic relationships, and wherein the semantic relationship extraction phase further comprises: program instructions to extract a semantic relationship from each stored identified sentence, wherein the semantic relationship comprises a subject, a predicate, and an object; responsive to extracting and identifying the semantic relationship, program instructions to apply statistical distribution analysis to record a position where the subject and the object appear in the document; program instructions to identify and eliminate a trivial relation, wherein the trivial relation does not relate to a main topic of the document and based on the trivial relation having at least one of: the subject being evenly distributed within a section of the document, wherein a section is selected from a group consisting of a sentence, a paragraph, a page, a chapter, and the document as a whole; and the object being evenly distributed within the section of the document; and program instructions to store a non-trivial relation in persistent storage; in response to completing the semantic relationship extraction phase, program instructions to execute an analytics and relevance determination phase wherein the analytics and relevance determination phase comprises program instructions to identify candidate appendix topics in the stored extracted semantic relationships based on a degree of interdependency between the semantic relationships and program instructions to store the identified candidate appendix topics; in response to completing the analytics and relevance determination phase, program instructions to execute a web mining phase wherein the web mining phase comprises program instructions to calculate a measure of relevance of the mined web page to the stored candidate appendix topics and eliminate non-relevant intermediate results; and based on the web mining phase returning results relevant to a topic of the document, program instructions to generate the appendix.