Clarifying maximum number of distinct station names

README.md

@@ -123,6 +123,7 @@ If you want to use a build not available via these channels, reach out to discus
 * Input value ranges are as follows:
     * Station name: non null UTF-8 string of min length 1 character and max length 100 characters
     * Temperature value: non null double between -99.9 (inclusive) and 99.9 (inclusive), always with one fractional digit
+* There is a maximum of 10,000 unique station names
 * Implementations must not rely on specifics of a given data set, e.g. any valid station name as per the constraints above and any data distribution (number of measurements per station) must be supported
 
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