Minor changes

- Added missing environment variables to Dockerfile
- Constant ca certificates filepath
- Removed dns/os.go unused file
- Formatting improvements
- Added comments
- Readme TODOs update

Dockerfile

@@ -36,6 +36,9 @@ ENV USER= \
     REGION="CA Montreal" \
     DOT=on \
     DOT_PROVIDERS=cloudflare \
+    DOT_VERBOSITY=1 \
+    DOT_VERBOSITY_DETAILS=0 \
+    DOT_VALIDATION_LOGLEVEL=0 \
     BLOCK_MALICIOUS=on \
     BLOCK_SURVEILLANCE=off \
     BLOCK_ADS=off \