the synopsis is missing when running in the build tree:

i22 : help merge

o22 = merge
      *****



      Description
      ===========

      If x and y have the same class and parent, then so will z.

      This function is useful for multiplying monomials or adding polynomials.  We illustrate that with a simple-minded implementation of the free abelian
      group on the set of strings, representing an element as a type of hash table that associates coefficients to strings.

