Bump acorn from 6.1.0 to 6.4.1 in /docs (#656)

Bumps [acorn](https://github.com/acornjs/acorn) from 6.1.0 to 6.4.1.
- [Release notes](https://github.com/acornjs/acorn/releases)
- [Commits](acornjs/acorn@6.1.0...6.4.1)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

docs/yarn.lock

@@ -1111,9 +1111,9 @@ acorn-dynamic-import@^4.0.0:
   integrity sha512-d3OEjQV4ROpoflsnUA8HozoIR504TFxNivYEUi6uwz0IYhBkTDXGuWlNdMtybRt3nqVx/L6XqMt0FxkXuWKZhw==
 
 acorn@^6.0.5:
-  version "6.1.0"
-  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.1.0.tgz#b0a3be31752c97a0f7013c5f4903b71a05db6818"
-  integrity sha512-MW/FjM+IvU9CgBzjO3UIPCE2pyEwUsoFl+VGdczOPEdxfGFjuKny/gN54mOuX7Qxmb9Rg9MCn2oKiSUeW+pjrw==
+  version "6.4.1"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.1.tgz#531e58ba3f51b9dacb9a6646ca4debf5b14ca474"
+  integrity sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==
 
 ajv-errors@^1.0.0:
   version "1.0.1"