yplan: add page (#10785)

* Adding page for yplan

* Capitalize first letter

* addressed comments

pages/linux/yplan.md

@@ -0,0 +1,9 @@
+# yplan
+
+> Generate LaTeX code for a two-page vertical daily planner for any chosen year.
+> The generated output can be converted or printed using conversion tools such as `pandoc`, `pdflatex`, or `xetex`.
+> More information: <https://www.ctan.org/tex-archive/macros/latex/contrib/yplan>.
+
+- Create a daily planner with specified language, lettercase (uppercase or lowercase) and year:
+
+`yplan {{language}} {{lettercase}} {{year}} > {{path/to/file.tex}}`