Move two non-equation images from Eqs folder to JPG folder

doc/src/improper_fourier.txt

@@ -27,7 +27,7 @@ The {fourier} improper style uses the following potential:
 where K is the force constant and omega is the angle between the IL
 axis and the IJK plane:
 
-:c,image(Eqs/umbrella.jpg)
+:c,image(JPG/umbrella.jpg)
 
 If all parameter (see bellow) is not zero, the all the three possible angles will taken in account.
 

doc/src/improper_inversion_harmonic.txt

@@ -28,7 +28,7 @@ where K is the force constant and omega is the angle evaluated for
 all three axis-plane combinations centered around the atom I.  For
 the IL axis and the IJK plane omega looks as follows:
 
-:c,image(Eqs/umbrella.jpg)
+:c,image(JPG/umbrella.jpg)
 
 Note that the {inversion/harmonic} angle term evaluation differs to
 the "improper_umbrella"_improper_umbrella.html due to the cyclic

doc/src/improper_umbrella.txt

@@ -29,7 +29,7 @@ commonly referred to as a classic inversion and used in the
 where K is the force constant and omega is the angle between the IL
 axis and the IJK plane:
 
-:c,image(Eqs/umbrella.jpg)
+:c,image(JPG/umbrella.jpg)
 
 If omega0 = 0 the potential term has a minimum for the planar
 structure.  Otherwise it has two minima at +/- omega0, with a barrier

doc/src/pair_hbond_dreiding.txt

@@ -46,7 +46,7 @@ Here, {r} is the radial distance between the donor (D) and acceptor
 (A) atoms and {theta} is the bond angle between the acceptor, the
 hydrogen (H) and the donor atoms:
 
-:c,image(Eqs/dreiding_hbond.jpg)
+:c,image(JPG/dreiding_hbond.jpg)
 
 These 3-body interactions can be defined for pairs of acceptor and
 donor atoms, based on atom types.  For each donor/acceptor atom pair,