Remove broken links.

docs.it4i/software/chemistry/orca.md

@@ -17,8 +17,6 @@ $ ml av orca
 You can test a serial computation with this simple input file. Create a file called orca_serial.inp and fill it with the following ORCA commands:
 
 ```bash
-    # Taken from the Orca manual
-    # https://orcaforum.cec.mpg.de/OrcaManual.pdf
     ! HF SVP
     * xyz 0 1
       C 0 0 0
@@ -87,8 +85,6 @@ Your serial computation can be easily converted to parallel. Simply specify the
     Do not use the `! PAL` directive as only PAL2 to PAL8 is recognized.
 
 ```bash
-    # Taken from the Orca manual
-    # https://orcaforum.cec.mpg.de/OrcaManual.pdf
     ! HF SVP
     %pal
       nprocs 512 # 4 nodes, 128 cores each