include added docpages in toctrees for sphinx

doc/src/angles.txt

@@ -8,6 +8,7 @@ Angle Styles :h1
    angle_charmm
    angle_class2
    angle_cosine
+   angle_cosine_buck6d
    angle_cosine_delta
    angle_cosine_periodic
    angle_cosine_shift

doc/src/impropers.txt

@@ -12,6 +12,7 @@ Improper Styles :h1
    improper_fourier
    improper_harmonic
    improper_hybrid
+   improper_inversion_harmonic
    improper_none
    improper_ring
    improper_umbrella

doc/src/pairs.txt

@@ -17,6 +17,7 @@ Pair Styles :h1
    pair_brownian
    pair_buck
    pair_buck_long
+   pair_buck6d_coul_gauss
    pair_charmm
    pair_class2
    pair_colloid