correct 'thrid' instead of 'third'

doc/src/python.txt

@@ -310,7 +310,7 @@ which corresponds to SELF in the python command.  The first line of
 the function imports the Python module lammps.py in the python dir of
 the distribution.  The second line creates a Python object "lmp" which
 wraps the instance of LAMMPS that called the function.  The
-"ptr=lmpptr" argument is what makes that happen.  The thrid line
+"ptr=lmpptr" argument is what makes that happen.  The third line
 invokes the command() function in the LAMMPS library interface.  It
 takes a single string argument which is a LAMMPS input script command
 for LAMMPS to execute, the same as if it appeared in your input

src/USER-MISC/improper_ring.cpp

@@ -204,7 +204,7 @@ void ImproperRing::compute(int eflag, int vflag)
          cfact2 = ckjji / ckjkj;
          cfact3 = ckjji / cjiji;
 
-         /* Calculate the force acted on the thrid atom of the angle. */
+         /* Calculate the force acted on the third atom of the angle. */
          fkx = cfact2 * bvec2x[icomb] - bvec1x[icomb];
          fky = cfact2 * bvec2y[icomb] - bvec1y[icomb];
          fkz = cfact2 * bvec2z[icomb] - bvec1z[icomb];

src/USER-OMP/improper_ring_omp.cpp

@@ -206,7 +206,7 @@ void ImproperRingOMP::eval(int nfrom, int nto, ThrData * const thr)
         cfact2 = ckjji / ckjkj;
         cfact3 = ckjji / cjiji;
 
-        /* Calculate the force acted on the thrid atom of the angle. */
+        /* Calculate the force acted on the third atom of the angle. */
         fkx = cfact2 * bvec2x[icomb] - bvec1x[icomb];
         fky = cfact2 * bvec2y[icomb] - bvec1y[icomb];
         fkz = cfact2 * bvec2z[icomb] - bvec1z[icomb];