feat: add new category for examples

Author: ilyar

src/solidity-by-example/_category_.json

@@ -0,0 +1,9 @@
+{
+  "position": 0,
+  "label": "Solidity by example",
+  "link": {
+    "title": "Solidity by example",
+    "slug": "solidity-by-example",
+    "type": "generated-index"
+  }
+}

src/solidity-by-example/application/_category_.json

@@ -0,0 +1,9 @@
+{
+  "position": 2,
+  "label": "Application",
+  "link": {
+    "title": "Application",
+    "slug": "application",
+    "type": "generated-index"
+  }
+}

src/solidity-by-example/basic/_category_.json

@@ -0,0 +1,8 @@
+{
+  "position": 0,
+  "label": "Basic",
+  "link": {
+    "slug": "solidity-by-example/basic",
+    "type": "generated-index"
+  }
+}

src/solidity-by-example/basic/first-app.md

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+---
+sidebar_position: 2
+title: First Application
+description: Specifies the compiler version of Solidity
+---
+
+Here is a simple contract that you can get, increment and decrement the count store in this contract.
+
+```solidity
+// SPDX-License-Identifier: MIT
+pragma ever-solidity ^0.70.0;
+
+contract Counter {
+    uint public count;
+
+    // Function to increment count by 1
+    function inc() public {
+        // This action is required to process external messages that bring no value
+        tvm.accept();
+        count += 1;
+    }
+
+    // Function to decrement count by 1
+    function dec() public {
+        // This action is required to process external messages that bring no value
+        tvm.accept();
+        // This function will fail if count = 0
+        count -= 1;
+    }
+}
+```
+
+## Deploying the contract
+
+```shell
+npx everdev sol compile first-app.sol
+npx everdev contract deploy first-app -v 100000000
+```
+
+## Interacting with the contract
+
+```shell
+npx everdev contract run first-app inc
+npx everdev contract run-local first-app count
+npx everdev contract run first-app dec
+npx everdev contract run-local first-app count
+```

src/solidity-by-example/basic/hello-world.md

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+---
+sidebar_position: 1
+title: "Hello World"
+description: Specifies the compiler version of Solidity
+---
+
+`pragma` specifies the compiler version of Solidity.
+
+
+```solidity
+// SPDX-License-Identifier: MIT
+// compiler version must be greater than or equal to 0.70.0 and less than 0.71.0
+pragma ever-solidity ^0.70.0;
+
+contract HelloWorld {
+    string public greet = "Hello World!";
+}
+```
+
+## Deploying the contract
+
+```shell
+npx everdev sol set --compiler 0.70.0
+npx everdev sol compile hello-world.sol
+npx everdev contract deploy hello-world -v 100000000
+```
+
+## Interacting with the contract
+
+```shell
+npx everdev contract run-local hello-world greet
+```

src/solidity-by-example/hack/_category_.json

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+{
+  "position": 3,
+  "label": "Hack",
+  "link": {
+    "title": "Hack",
+    "slug": "hack",
+    "type": "generated-index"
+  }
+}