Remove docs for removed command

reference/rpc/generate.rst

-.. This file is licensed under the MIT License (MIT) available on
-   http://opensource.org/licenses/MIT.
-
-generate
-========
-
-``generate nblocks ( maxtries )``
-
-Mine up to nblocks blocks immediately (before the RPC call returns) to an address in the wallet.
-
-Argument #1 - nblocks
-~~~~~~~~~~~~~~~~~~~~~
-
-**Type:** numeric, required
-
-How many blocks are generated immediately.
-
-Argument #2 - maxtries
-~~~~~~~~~~~~~~~~~~~~~~
-
-**Type:** numeric, optional, default=1000000
-
-How many iterations to try.
-
-Result
-~~~~~~
-
-::
-
-  [ blockhashes ]     (array) hashes of blocks generated
-
-Examples
-~~~~~~~~
-
-
-.. highlight:: shell
-
-Generate 11 blocks::
-
-  bitcoin-cli generate 11
-