Add mStable MTA and update mStable mUSD (#2748)

* Update mUSD logo

* Add MTA logo

* Update mUSD/MTA descriptions

blockchains/ethereum/assets/0xa3BeD4E1c75D00fa6f4E5E6922DB7261B5E9AcD2/info.json

@@ -0,0 +1,9 @@
+{
+  "name": "Meta",
+  "website": "https://mstable.org",
+  "short_description": "mStable unites stablecoins, lending and swapping into one standard.",
+  "socials": [
+    "https://twitter.com/mstable_"
+  ],
+  "explorer": "https://etherscan.io/token/0xa3BeD4E1c75D00fa6f4E5E6922DB7261B5E9AcD2"
+}

blockchains/ethereum/assets/0xe2f2a5C287993345a840Db3B0845fbC70f5935a5/info.json

@@ -1,7 +1,7 @@
 {
     "name": "mStable USD",
     "website": "https://mstable.org",
-    "short_description": "mStable makes stablecoins easy, robust & profitable.",
+    "short_description": "mStable unites stablecoins, lending and swapping into one standard.",
     "socials": [
         "https://twitter.com/mstable_"
     ],