docs: fix Discord link and environment variable typo

[defiberrys]

Hey, I noticed a couple of issues while going through the docs:

1. Fixed the Discord link—it was incorrect.
2. Corrected a typo in the environment variable name: GOMELIMIT=40GB → GOMEMLIMIT=40GB.

Just a quick fix to avoid confusion.

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Name	Status	Preview	Comments	Updated (UTC)
0g-doc-new	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Mar 27, 2025 7:05am

[udhaykumarbala]

📢 Documentation Restructure Update

Thank you for your contribution to the 0G documentation!

We have recently completed a major restructure and revamp of our entire
documentation system. This includes:

• ✨ New architecture with improved organization and navigation
• 🔧 Enhanced CI/CD pipeline with automated quality checks
• 🎯 Streamlined contribution workflow for better collaboration

🔄 Next Steps

Due to the extensive changes, this PR is no longer compatible with the
current documentation structure. However, your contribution is still
valuable!

If you'd like to continue contributing:

1. 📖 Review our new ./CONTRIBUTING.md for updated processes and
   standards
2. 🔍 Check if your suggestion is still relevant in the new structure
3. 🆕 Create a new issue using our issue templates to propose your
   changes
4. 🚀 Submit a fresh PR following the new guidelines

🤝 We Value Your Input

Your feedback and contributions help make our documentation better for
everyone. We encourage you to engage with our new contribution system -
it's designed to make collaboration smoother and more effective.

Questions? Feel free to:

• 💬 Join our https://github.com/0glabs/0g-doc/discussions
• 📝 Create a new issue with our templates
• 🔄 Reference this PR in any new contributions

Thank you for being part of the 0G community! 🙏

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This PR is being closed due to documentation restructure. No action
required on your part.