The Free On-line Dictionary of Computing (19 January 2023):

brain dump

   (The act of telling someone) everything one knows about a
   particular topic.  Typically used when someone is going to let
   a new party maintain a piece of code.  Conceptually analogous
   to an operating system core dump in that it saves a lot of
   useful state before an exit.  "You'll have to give me a
   brain dump on FOOBAR before you start your new job at
   HackerCorp."  At Sun, this is also known as "TOI" (transfer of
   information).

   [Jargon File]


The Jargon File (version 4.4.7, 29 Dec 2003):

brain dump
 n.

    [common] The act of telling someone everything one knows about a particular
    topic or project. Typically used when someone is going to let a new party
    maintain a piece of code. Conceptually analogous to an operating system 
    core dump in that it saves a lot of useful state before an exit. “You'll
    have to give me a brain dump on FOOBAR before you start your new job at
    HackerCorp.” See core dump (sense 4). At Sun, this is also known as TOI
    (transfer of information).