Various documentation updates (#333)

* Add a note about socket sharing

* Show inherited members for apidocs

* Remove outdated note of emeters not being supported on smartstrips

* Describe emeter and usage modules, add note about NTP for time sync

* Describe lib design and modules

* Bump sphinx version, ignore d001 (line-length) for doc8

* demote energy & usage to 3rd level, promote api for 2nd

.pre-commit-config.yaml

@@ -37,3 +37,9 @@ repos:
   hooks:
   - id: mypy
     additional_dependencies: [types-click]
+
+- repo: https://github.com/PyCQA/doc8
+  rev: '0.11.1'
+  hooks:
+  - id: doc8
+    additional_dependencies: [tomli]