Correct three comments.

examples/xspice/ghdl/README.txt

@@ -27,7 +27,7 @@ mechanical quantities do not match standard units.
 
 Before a simulation can be run, the associated VHDL code must be compiled
 and an additional shared library, ghdlng.vpi must be built.  A library script
-isavailable to simplify the steps, run like this:
+is available to simplify the steps, run like this:
 
     ngspice ghnggen adc.vhd
 

src/xspice/icm/digital/d_cosim/cfunc.mod

@@ -118,7 +118,7 @@ static void callback(ARGS, Mif_Callback_Reason_t reason)
     }
 }
 
-/* A utility function used to open static libraries, trying an installation
+/* A utility function used to open dynamic libraries, trying an installation
  * directory and different file extenstions.
  */
 

src/xspice/vhdl/ghdl_vpi.c

@@ -31,7 +31,7 @@
 #include <pthread.h>
 #endif
 
-/* The VVP code runs on its own stack, handled by cr_xxx() functions. */
+/* The VHDL code runs on its own stack, handled by cr_xxx() functions. */
 
 #include "ngspice/coroutine_cosim.h"