Add rewrite patterns for hermes to documentation

[Stas-Buzunko]

Rollbar v0.9.3

There are at least two open issues related to sourcemaps problems associated with Hermes. So, it might be worth adding to the documentation (assuming these patterns might have been added to v1).

Issues:
#124
#151 (comment)

If anyone faces these problems, here are the patterns that worked for me:

rewriteFilenamePatterns: [
    Platform.OS === 'ios' ? '([^/]*)$' : '^address at (.*)$'
]