Update MainIdealGasLawCalc.js

[DapaoK]

Issue Id you have worked upon -

573

Briefly explain your program logic -

PV=nRT There are two types of units in GasConstant（atm·L/(mol·K) and J/(mol·K)）

Screenshots(Attach 2 screenshots of your own input and output) -

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[Vedansh-Keshari]

Congratulations 🎉 @DapaoK on your contribution. Thanks for adding value to this repository. 😊

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[Vedansh-Keshari]

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