Add note about parameters in source strings

README.md

@@ -4,6 +4,25 @@ This repository is used to translate CryptoZombies to other languages.
 
 The source content that should be used for all translations is in the `en` directory.
 
+```
+en/
+  1/ - content of Lesson 1
+  ...
+  N/ - content of Lesson N
+  index.json - strings used in the UI
+  share-template-msgs.json - strings used on the share page
+```
+
+Strings in `index.json` and `share-template-msgs.json` can contain parameters,
+these will be injected before the strings are displayed to the user. Parameters
+that are present in the source strings may appear in any position in the
+translated strings, or omitted entirely if it makes sense to do so.
+
+>NOTE: The syntax used to represent parameters differs between the two `.json`
+>      files. In `index.json` parameters are specified using `{parameterName}`,
+>      while in `share-template-msgs.json` parameters are specified using
+>      `{{ .ParameterName }}`.
+
 ## Localizing for a new language
 1. Create a new branch off `master`.
 2. Create a new folder named after the locale code, e.g. `jp` (for Japanese), `zh` (for Chinese).