Update README instructions for regenerating the nanopb for Crashlytics (#4886)

Author: samedson

Crashlytics/README.md

@@ -26,9 +26,9 @@ testing the FirebaseCrashlytics CocoaPod.
 
 If the crash report proto needs to be updated, follow these instructions -
 - Prerequisite installations:
-    - gem (update|install) cocoapods cocoapods-generate
-    - brew install protobuf nanopb
-    - easy_install protobuf python
+    - `gem (update|install) cocoapods cocoapods-generate`
+    - `brew install protobuf nanopb-generator`
+    - `easy_install protobuf python`
 - Update `ProtoSupport/Protos/crashlytics.proto` with the new changes
 - Depending on the type of fields added/removed, also update `ProtoSupport/Protos/crashlytics.options`.
  `CALLBACK` type fields in crashlytics.nanopb.c needs to be changed to `POINTER`