add support for the conversion of ePUB to MOBI (compatible with Kindle)

doc/Makefile

@@ -31,7 +31,7 @@ SPHINXEXTRA = -j $(shell $(PYTHON) -c 'import multiprocessing;print(multiprocess
 SOURCES=$(filter-out $(wildcard src/lammps_commands*.txt) src/lammps_support.txt src/lammps_tutorials.txt,$(wildcard src/*.txt))
 OBJECTS=$(SOURCES:src/%.txt=$(RSTDIR)/%.rst)
 
-.PHONY: help clean-all clean epub html pdf old venv spelling anchor_check
+.PHONY: help clean-all clean epub mobi html pdf old venv spelling anchor_check
 
 # ------------------------------------------
 
@@ -42,6 +42,7 @@ help:
 	@echo "  old        create old-style HTML doc pages in old dir"
 	@echo "  fetch      fetch HTML and PDF files from LAMMPS web site"
 	@echo "  epub       create ePUB format manual for e-book readers"
+	@echo "  mobi       create MOBI format manual for e-book readers (e.g. Kindle)"
 	@echo "  clean      remove all intermediate RST files"
 	@echo "  clean-all  reset the entire build environment"
 	@echo "  txt2html   build txt2html tool"
@@ -106,6 +107,11 @@ epub: $(OBJECTS)
 	@rm -rf epub
 	@echo "Build finished. The ePUB manual file is created."
 
+mobi: epub
+	@rm -f LAMMPS.mobi
+	@ebook-convert LAMMPS.epub LAMMPS.mobi
+	@echo "Conversion finished. The MOBI manual file is created."
+
 pdf: utils/txt2html/txt2html.exe
 	@(\
 		set -e; \