Fix Grammar

README.md

 ###### fireice-uk's and psychocrypt's
 # XMR-Stak - Cryptonight All-in-One Mining Software
 
-XMR-Stak is a universal Stratum pool miner. This miner supports CPUs, AMD and NVIDIA gpus and can be used to mine the crypto currencys Monero, Aeon and many more Cryptonight coins.
+XMR-Stak is a universal Stratum pool miner. This miner supports CPUs, AMD and NVIDIA GPUs and can be used to mine the crypto currencies Monero, Aeon and many more Cryptonight coins.
 
 ## HTML reports
 <img src="https://gist.githubusercontent.com/fireice-uk/2da301131ac01695ff79539a27b81d68/raw/4c09cdeee86f94df2e9dd86b927e64aded6184f5/xmr-stak-cpu-hashrate.png" width="260"> <img src="https://gist.githubusercontent.com/fireice-uk/2da301131ac01695ff79539a27b81d68/raw/4c09cdeee86f94df2e9dd86b927e64aded6184f5/xmr-stak-cpu-results.png" width="260"> <img src="https://gist.githubusercontent.com/fireice-uk/2da301131ac01695ff79539a27b81d68/raw/4c09cdeee86f94df2e9dd86b927e64aded6184f5/xmr-stak-cpu-connection.png" width="260">
@@ -28,7 +28,7 @@ XMR-Stak is a universal Stratum pool miner. This miner supports CPUs, AMD and NV
 - supports algorithm cryptonight for Monero (XMR) and cryptonight-light (AEON)
 - easy to use
   - guided start (no need to edit a config file for the first start)
-  - auto configuration for each backend
+  - auto-configuration for each backend
 - open source software (GPLv3)
 - TLS support
 - [HTML statistics](doc/usage.md#html-and-json-api-report-configuraton)
@@ -64,7 +64,7 @@ If your prefered coin is not listed, you can choose one of the following algorit
     - cryptonight_haven
     - cryptonight_heavy
 
-Please note, this list is not complete, and is not an endorsement.
+Please note, this list is not complete and is not an endorsement.
 
 ## Download
 
@@ -72,7 +72,7 @@ You can find the latest releases and precompiled binaries on GitHub under [Relea
 
 ## Default Developer Donation
 
-By default the miner will donate 2% of the hashpower (2 minute in 100 minutes) to my pool. If you want to change that, edit [donate-level.hpp](xmrstak/donate-level.hpp) before you build the binaries.
+By default, the miner will donate 2% of the hashpower (2 minutes in 100 minutes) to my pool. If you want to change that, edit [donate-level.hpp](xmrstak/donate-level.hpp) before you build the binaries.
 
 If you want to donate directly to support further development, here is my wallet