chore: remove note about editable installs (#92)

`pip install -e .` is supported and is how we install the library for tests.
    
Source-Author: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>
Source-Date: Tue Sep 22 12:06:12 2020 -0600
Source-Repo: googleapis/synthtool
Source-Sha: a651c5fb763c69a921aecdd3e1d8dc51dbf20f8d
Source-Link: googleapis/synthtool@a651c5f

Author: yoshi-automation

packages/google-cloud-datastore/CONTRIBUTING.rst

@@ -80,25 +80,6 @@ We use `nox <https://nox.readthedocs.io/en/latest/>`__ to instrument our tests.
 
 .. nox: https://pypi.org/project/nox/
 
-Note on Editable Installs / Develop Mode
-========================================
-
-- As mentioned previously, using ``setuptools`` in `develop mode`_
-  or a ``pip`` `editable install`_ is not possible with this
-  library. This is because this library uses `namespace packages`_.
-  For context see `Issue #2316`_ and the relevant `PyPA issue`_.
-
-  Since ``editable`` / ``develop`` mode can't be used, packages
-  need to be installed directly. Hence your changes to the source
-  tree don't get incorporated into the **already installed**
-  package.
-
-.. _namespace packages: https://www.python.org/dev/peps/pep-0420/
-.. _Issue #2316: https://github.com/GoogleCloudPlatform/google-cloud-python/issues/2316
-.. _PyPA issue: https://github.com/pypa/packaging-problems/issues/12
-.. _develop mode: https://setuptools.readthedocs.io/en/latest/setuptools.html#development-mode
-.. _editable install: https://pip.pypa.io/en/stable/reference/pip_install/#editable-installs
-
 *****************************************
 I'm getting weird errors... Can you help?
 *****************************************

packages/google-cloud-datastore/synth.metadata

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/python-datastore.git",
-        "sha": "ddbbb03fc42bf53e698b3869a660a9938b3339e8"
+        "sha": "8aa3eac28e0e733b61d6ab9e1d233a99467b7081"
       }
     },
     {