[DOCS] Update docs dependency versions and remove unneeded arguments

Makefile

@@ -225,15 +225,15 @@ docs-container:
 # shell).
 .PHONY: docs-build
 docs-build: docs-container
-	docker run -v $(PWD):/m3db --rm m3db-docs "mkdocs build -e docs/theme -t material"
+	docker run -v $(PWD):/m3db --rm m3db-docs "mkdocs build -t material"
 
 .PHONY: docs-serve
 docs-serve: docs-container
-	docker run -v $(PWD):/m3db -p 8000:8000 -it --rm m3db-docs "mkdocs serve -e docs/theme -t material -a 0.0.0.0:8000"
+	docker run -v $(PWD):/m3db -p 8000:8000 -it --rm m3db-docs "mkdocs serve -t material -a 0.0.0.0:8000"
 
 .PHONY: docs-deploy
 docs-deploy: docs-container
-	docker run -v $(PWD):/m3db --rm -v $(HOME)/.ssh/id_rsa:/root/.ssh/id_rsa:ro -it m3db-docs "mkdocs build -e docs/theme -t material && mkdocs gh-deploy --force --dirty"
+	docker run -v $(PWD):/m3db --rm -v $(HOME)/.ssh/id_rsa:/root/.ssh/id_rsa:ro -it m3db-docs "mkdocs build -t material && mkdocs gh-deploy --force --dirty"
 
 .PHONY: docs-validate
 docs-validate: docs_test

docs/Dockerfile

@@ -10,8 +10,7 @@ EXPOSE 8000
 # mkdocs needs git-fast-import which was stripped from the default git package
 # by default to reduce size
 RUN pip install \
-    mkdocs==0.17.3 \
-    pymdown-extensions==6.0 \
-    mkdocs-material==2.7.3
+    nltk==3.4.5 \
+    mkdocs-material==5.5.3
 RUN apk add --no-cache git-fast-import openssh-client
 ENTRYPOINT [ "/bin/ash", "-c" ]