Update README.rst
Update README.rst

Add Analytics Cloud to the list of projects using C++ Format.
Source: https://help.salesforce.com/servlet/servlet.FileDownload?file=015300000035w3yAAA
wangshijin/cppformat,blaquee/cppformat,dean0x7d/cppformat,wangshijin/cppformat,lightslife/cppformat,dean0x7d/cppformat,nelson4722/cppformat,Jopie64/cppformat,nelson4722/cppformat,seungrye/cppformat,cppformat/cppformat,cppformat/cppformat,blaquee/cppformat,mojoBrendan/fmt,seungrye/cppformat,blaquee/cppformat,Jopie64/cppformat,lightslife/cppformat,mojoBrendan/fmt,dean0x7d/cppformat,lightslife/cppformat,alabuzhev/fmt,wangshijin/cppformat,alabuzhev/fmt,nelson4722/cppformat,mojoBrendan/fmt,cppformat/cppformat,seungrye/cppformat,Jopie64/cppformat,alabuzhev/fmt