obabel: add page (#10096)

* obabel: add page
---------

Co-authored-by: Jack Lin <blueskyson1401@gmail.com>

pages/linux/obabel.md

@@ -0,0 +1,20 @@
+# obabel
+
+> Translate chemistry-related data.
+> More information: <https://openbabel.org/wiki/Main_Page>.
+
+- Convert a .mol file to XYZ coordinates:
+
+`obabel {{path/to/file.mol}} -O {{path/to/output_file.xyz}}`
+
+- Convert a SMILES string to a 500x500 picture:
+
+`obabel -:"{{SMILES}} -O {{path/to/output_file.png}} -xp 500`
+
+- Convert a file of SMILES string to separate 3D .mol files:
+
+`obabel {{path/to/file.smi}} -O {{path/to/output_file.mol}} --gen3D -m`
+
+- Render multiple inputs into one picture:
+
+`obabel {{path/to/file1}} {{path/to/file2}} -O {{path/to/output_file.png}}`