message: Update README.md
  change before_cache to before_script
diff: @@ -256,7 +256,7 @@ matrix:
  allow_failures:
  - rust: nightly
  -before_cache: |
  +before_script: |
  if [[ "$TRAVIS_RUST_VERSION" == stable ]]; then
  cargo install cargo-tarpaulin
  fi
  @@ -277,6 +277,10 @@ after_success: |
  fi
  ```
  +If you rely on certain nightly features you may need to change the `before_script` to
  +`before_cache` to force tarpaulin to reinstall each time. However, if it can be avoided it
  +will speed up your CI runs.
  +
  Alternatively, there are the prebuilt docker images or the travis-install shell script.
  The travis-install script will install the latest tagged release built on travis to your
  travis instance and significantly speeds up the travis builds. You can install via that script
  