dev-manual/start.rst: remove basic setup for hash equivalence

Quoting Alexander Kanavin [1]:

> 1. BB_HASHSERVE and BB_SIGNATURE_HANDLER do not set up or start a
> server, they set up the hash equivalence client built into bitbake.
>
> 2. The above client configuration (used by poky) also starts a private
> server that is specific to a particular build directory. So hash equiv
> information would not be shared between multiple build directories,
> and this will cause sstate mismatches (as reported in the bug), if
> sstate is shared.

This setup does not shed light on the potential of the hash equivalence
feature. So for now, remove this basic setup, and later rework the
concepts (or create a new) document that explains how to set up a hash
equivalence server shared between builds.

[1]: https://lore.kernel.org/r/CANNYZj_kvLsZG3sgH+nPu9B=pqWBU785w0SGHGdQqB4UW-DtmA@mail.gmail.com

Suggested-by: Alexander Kanavin <alex.kanavin@gmail.com>
(From yocto-docs rev: 71c8b839e2621a048361d5518104099fee0f9e52)

Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
(cherry picked from commit 231fc9e710ab34db60263f8ae01d4f5970579203)
Signed-off-by: Antonin Godard <antonin.godard@bootlin.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

documentation/dev-manual/start.rst

@@ -228,12 +228,7 @@ particular working environment and set of practices.
        used by developers in the same organization and share the same
        source directories on their machines.
 
-    -  Set up a local :ref:`overview-manual/concepts:Hash Equivalence` server
-       with :term:`BB_HASHSERVE` and :term:`BB_SIGNATURE_HANDLER`. A basic setup
-       would be::
-
-          BB_HASHSERVE = "auto"
-          BB_SIGNATURE_HANDLER = "OEEquivHash"
+    -  Set up a local :ref:`overview-manual/concepts:Hash Equivalence` server.
 
        See the :ref:`overview-manual/concepts:Hash Equivalence` section of the
        Yocto Project Overview and Concepts Manual for more details on the hash