Add package level documentation and citation information

Change-Id: I109311d37747d7c65bd7db893f10e25ebe432e3a
diff --git a/DESCRIPTION b/DESCRIPTION
index 418805e..0b416f1 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -26,5 +26,6 @@
 Collate: 
     'utils-pipe.R'
     'derekovecs.R'
+    'rderekovecs-package.R'
 Roxygen: list(markdown = TRUE)
 Config/testthat/edition: 3
diff --git a/NAMESPACE b/NAMESPACE
index 0ac2973..bcf44e9 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -13,3 +13,4 @@
 importFrom(httr2,request)
 importFrom(httr2,resp_body_json)
 importFrom(magrittr,"%>%")
+importFrom(utils,citation)
diff --git a/R/rderekovecs-package.R b/R/rderekovecs-package.R
new file mode 100644
index 0000000..213d96f
--- /dev/null
+++ b/R/rderekovecs-package.R
@@ -0,0 +1,15 @@
+#' @keywords internal
+"_PACKAGE"
+
+## usethis namespace: start
+#' @importFrom utils citation
+
+.onAttach<-function(libname, pkgname){
+  requireNamespace("utils")
+  cit<-citation(pkgname)
+  txt<-paste(c(format(cit,"citation")),collapse="\n\n")
+  packageStartupMessage(txt)
+}
+
+## usethis namespace: end
+NULL
diff --git a/inst/CITATION b/inst/CITATION
new file mode 100644
index 0000000..338ad64
--- /dev/null
+++ b/inst/CITATION
@@ -0,0 +1,14 @@
+bibentry(
+  bibtype  = "InCollection",
+	title = "Count-based and predictive language models for exploring {DeReKo}",
+	booktitle = "Proceedings of the {LREC} 2022 {Workshop} on {Challenges} in the {Management} of {Large} {Corpora} ({CMLC}-10)",
+
+	url = "http://www.lrec-conf.org/proceedings/lrec2022/workshops/CMLC10/pdf/2022.cmlc10-1.5.pdf",
+	publisher = "European Language Resources Association (ELRA)",
+	author = c(person("Peter", "Fankhauser"), person("Marc", "Kupietz")),
+	editor = c(person("Piotr", "BaƄski"), person("Adrien","Barbaresi"), person("Simon", "Clematide"), person("Marc", "Kupietz"), person("Harald", "Lüngen")),
+	year = "2022",
+	address = "Marseille/Paris",
+	pages = "27--31",
+  urn = "https://nbn-resolving.org/urn:nbn:de:bsz:mh39-111107"
+)
diff --git a/man/rderekovecs-package.Rd b/man/rderekovecs-package.Rd
new file mode 100644
index 0000000..01c8913
--- /dev/null
+++ b/man/rderekovecs-package.Rd
@@ -0,0 +1,23 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/rderekovecs-package.R
+\docType{package}
+\name{rderekovecs-package}
+\alias{rderekovecs}
+\alias{rderekovecs-package}
+\title{rderekovecs: DeReKoVecs API Client Package}
+\description{
+A client package that makes the 'DeReKoVecs' web service API accessible from R.
+}
+\seealso{
+Useful links:
+\itemize{
+  \item \url{https://korap.ids-mannheim.de/gerrit/plugins/gitiles/ids-kl/derekovecs}
+  \item \url{https://corpora.ids-mannheim.de/openlab/derekovecs}
+}
+
+}
+\author{
+\strong{Maintainer}: Marc Kupietz \email{kupietz@ids-mannheim.de}
+
+}
+\keyword{internal}