13. A computer program product for updating an existing document using natural language processing (NLP), the computer program product comprising: one or more computer-readable storage devices; program instructions, stored on at least one of the one or more storage devices, to receive information about a subject-matter domain; program instructions, stored on at least one of the one or more storage devices, to identify a portion of the existing document, wherein the portion corresponds to the subject-matter domain by including at least a threshold number of references to a category identified in the subject matter domain; program instructions, stored on at least one of the one or more storage devices, to lemmatize a group of words from the portion to use in a search query, wherein the search query returns a result set, the result set including current information corresponding to the subject-matter domain, the current information being recent as compared to an age of the portion; program instructions, stored on at least one of the one or more storage devices, to form natural language (NL) update content by processing the current information through an NLP application; program instructions, stored on at least one of the one or more storage devices, to associate with the NL update content a confidence rating, the confidence rating being indicative of a provenance of a data source that supplied the current information; and program instructions, stored on at least one of the one or more storage devices, to update, by changing the portion of the existing document in a document repository, the existing document using the NL update content and the confidence rating.
13. A computer program product for updating an existing document using natural language processing (NLP), the computer program product comprising: one or more computer-readable storage devices; program instructions, stored on at least one of the one or more storage devices, to receive information about a subject-matter domain; program instructions, stored on at least one of the one or more storage devices, to identify a portion of the existing document, wherein the portion corresponds to the subject-matter domain by including at least a threshold number of references to a category identified in the subject matter domain; program instructions, stored on at least one of the one or more storage devices, to lemmatize a group of words from the portion to use in a search query, wherein the search query returns a result set, the result set including current information corresponding to the subject-matter domain, the current information being recent as compared to an age of the portion; program instructions, stored on at least one of the one or more storage devices, to form natural language (NL) update content by processing the current information through an NLP application; program instructions, stored on at least one of the one or more storage devices, to associate with the NL update content a confidence rating, the confidence rating being indicative of a provenance of a data source that supplied the current information; and program instructions, stored on at least one of the one or more storage devices, to update, by changing the portion of the existing document in a document repository, the existing document using the NL update content and the confidence rating. 16. The computer program product of claim 13 , wherein the program instruction to update further comprises: program instructions, stored on at least one of the one or more storage devices, to modify a content of the portion in the existing document, wherein the modifying supplements the portion.