feat!: Adopted PEP-561 #4

BREAKING CHANGE: #4

Signed-off-by: Paul Horton <phorton@sonatype.com>

docs/index.rst

@@ -31,6 +31,7 @@ that can sacn your Python applications and utilise OSS Index data, why not check
    :caption: Contents:
 
    install
+   usage
    support
    changelog
 

docs/usage.rst

@@ -0,0 +1,59 @@
+.. # Copyright 2022-Present Sonatype Inc.
+   #
+   # Licensed under the Apache License, Version 2.0 (the "License");
+   # you may not use this file except in compliance with the License.
+   # You may obtain a copy of the License at
+   #
+   #     http://www.apache.org/licenses/LICENSE-2.0
+   #
+   # Unless required by applicable law or agreed to in writing, software
+   # distributed under the License is distributed on an "AS IS" BASIS,
+   # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   # See the License for the specific language governing permissions and
+   # limitations under the License.
+
+Usage
+============
+
+``ossindex-lib`` is designed to be included into other Python projects, not used as a standalone application.
+
+Library Configuration
+---------------------
+
+There are two key configurations that are possible:
+
+1. Caching of response from OSS Index
+2. Authentication for OSS Index
+
+Caching of OSS Index Responses
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+By default, caching is enabled and the cache will be stored in ``$HOME/.ossindex/``.
+
+You can disable caching as follows:
+
+.. code-block::
+
+  ossi = OssIndex(enable_cache=False)
+
+You can control the base directory where the cache directory ``.ossindex`` is created by supplying a directory as follows:
+
+.. code-block::
+
+  ossi = OssIndex(cache_location='/my/other/directory')
+
+In this last example, caching will be enabled and the cache will be stored in ``/my/other/directory/.ossindex``.
+
+Authenticating to OSS Index
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+By default, this library will attempt authenticated calls to OSS Index if authentication credentials exist in
+``$HOME/.oss-index.config``.
+
+``.oss-index.config`` is a YAML formatted file and the example below shows how a username and password can be added to
+enable authenticated calls to OSS Index:
+
+.. code-block::
+
+   username: my-oss-index-username
+   password: my-oss-index-password