Document the load src code from url, gist feature

README.md

@@ -24,6 +24,40 @@ Open [http://localhost:3000](http://localhost:3000) with your browser to see the
 
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+## Features
+
+### Loading Source Code from Gist or URL
+
+This feature allows users to load source code into the text box by providing either a URL or a GitHub Gist. It simplifies the process of compiling and running code from external sources, making it convenient for users to test and share code effortlessly.
+
+#### Loading Source Code from URL
+
+- Users can load source code by providing a URL directly in the format: `https://dev.lfortran.org/?code=<URL-encoded code>`.
+- The code provided via URL can be any valid Fortran code.
+
+##### Example URL:
+```
+https://dev.lfortran.org/?code=program%20hello%0A%20%20!%20This%20is%20a%20comment%20line%3B%20it%20is%20ignored%20by%20the%20compiler%0A%20%20print%20*%2C%20%27Hello%2C%20World!%27%0Aend%20program%20hello%0A
+```
+
+#### Loading Source Code from GitHub Gist
+
+- Alternatively, users can load source code from a GitHub Gist by providing the Gist URL in the format: `https://dev.lfortran.org/?gist=<GitHub username>/<Gist ID>`.
+- The compiler will fetch the raw content from the specified GitHub Gist.
+- **Note:** GitHub Gist takes approximately 5 minutes to update the raw content after any changes are made. As a result, there may be a delay of about 5 minutes before the updated content is reflected when loaded.
+
+##### Example GitHub Gist URL:
+```
+https://dev.lfortran.org/?gist=certik/7e2652943bbff7f0d0963dd4fcf1813a
+```
+
+#### Mutual Exclusivity
+
+- Users should be aware that if both a URL and a GitHub Gist are provided, the `code` parameter is given preference. Only the code provided via the `code` parameter will be considered for compilation.
+
+This feature enhances the versatility of the LFortran compiler, enabling users to seamlessly compile and run Fortran code from external sources without needing to download or manage local files.
+
+
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