gnu: Add texlive-apxproof.

* gnu/packages/tex.scm (texlive-apxproof): New variable.

gnu/packages/tex.scm

@@ -1528,6 +1528,32 @@ Operands may be numbers with arbitrary numbers of digits; scientific notation
 is allowed.  The expression scanner is also provided.")
     (license license:public-domain)))
 
+(define-public texlive-apxproof
+  (package
+    (name "texlive-apxproof")
+    (version (number->string %texlive-revision))
+    (source (texlive-origin
+             name version
+             (list "doc/latex/apxproof/"
+                   "source/latex/apxproof/"
+                   "tex/latex/apxproof/")
+             (base32
+              "1m4nvqxvnsllh25qmms6szcqqpb8wffk1z0v2p507fkgsdjz9jln")))
+    (outputs '("out" "doc"))
+    (build-system texlive-build-system)
+    (home-page "https://ctan.org/pkg/apxproof")
+    (synopsis "Proofs in appendix")
+    (description
+     "The package makes it easier to write articles where proofs and other
+material are deferred to the appendix.  The appendix material is written in
+the LaTeX code along with the main text which it naturally complements, and it
+is automatically deferred.  The package can automatically send proofs to the
+appendix, can repeat in the appendix the theorem environments stated in the
+main text, can section the appendix automatically based on the sectioning of
+the main text, and supports a separate bibliography for the appendix
+material.")
+    (license license:lppl1.3+)))
+
 (define-public texlive-arara
   (package
     (name "texlive-arara")