Updating the list of potentials in fix_adapt_fep.txt

There are several potentials that contain the method extract() but they are not included in the "fix adapt" and "fix adapt/fep"
A small update of the list is attempted here. The same potentials might be added to the documentation of fix_adapt if it is useful.

doc/src/fix_adapt_fep.txt

@@ -114,13 +114,23 @@ styles and their energy formulas for the meaning of these parameters:
 
 "born"_pair_born.html: a,b,c: type pairs:
 "buck"_pair_buck.html: a,c: type pairs:
+"buck/mdf"_pair_mdf.html: a,c: type pairs:
 "coul/cut"_pair_coul.html: scale: type pairs:
 "coul/debye"_pair_coul.html: scale: type pairs:
 "coul/long"_pair_coul.html: scale: type pairs:
+"gauss"_pair_gauss.html: a: type pairs:
+"lennard/mdf"_pair_mdf.html: A,B: type pairs:
+"lj/class2"_pair_class2.html: epsilon,sigma: type pairs:
+"lj/class2/coul/cut"_pair_class2.html: epsilon,sigma,coulombic_cutoff: type pairs:
 "lj/cut"_pair_lj.html: epsilon,sigma: type pairs:
 "lj/expand"_pair_lj_expand.html: epsilon,sigma,delta: type pairs:
+"lj/mdf"_pair_mdf.html: epsilon,sigma: type pairs:
 "lubricate"_pair_lubricate.html: mu: global:
-"gauss"_pair_gauss.html: a: type pairs:
+"mie/cut"_pair_mie.html: epsilon,sigma,gamma_repulsive,gamma_attractive: type pairs:
+"morse"_pair_morse.html: D0,R0,alpha: type pairs:
+"morse/soft"_pair_morse.html: D0,R0,alpha,lambda: type pairs:
+"nm/cut"_pair_nm.html: E0,R0,m,n: type pairs:
+"ufm"_pair_ufm.html: epsilon,sigma: type pairs:
 "soft"_pair_soft.html: a: type pairs :tb(c=3,s=:)
 
 NOTE: It is easy to add new potentials and their parameters to this