jp2a: add page (#4357)

pages/common/jp2a.md

@@ -0,0 +1,28 @@
+# jp2a
+
+> Convert JPEG images to ASCII.
+> More information: <https://csl.name/jp2a/>.
+
+- Read JPEG image from a file and print in ASCII:
+
+`jp2a {{path/to/image.jpeg}}`
+
+- Read JPEG image from a URL and print in ASCII:
+
+`jp2a {{www.example.com/image.jpeg}}`
+
+- Colorize the ASCII output:
+
+`jp2a --colors {{path/to/image.jpeg}}`
+
+- Specify characters to be used for the ASCII output:
+
+`jp2a --chars='{{..-ooxx@@}}' {{path/to/image.jpeg}}`
+
+- Write the ASCII output into a file:
+
+`jp2a --output={{path/to/output_file.txt}} {{path/to/image.jpeg}}`
+
+- Write the ASCII output in HTML file format, suitable for viewing in web browsers:
+
+`jp2a --html --output={{path/to/output_file.html}} {{path/to/image.jpeg}}`