feat: add gno belgrade (#73)

* chore: fixup

* chore: fixup

Author: leohhhn

README.md

@@ -9,6 +9,7 @@ presentations.
 
 |Date       |Title                                                                           |Speakers                                                                 |Presentation                                                                                                                                |Recording                                                                                            |
 |----       |-----                                                                           |--------                                                                 |------------                                                                                                                                |---------                                                                                            |
+|2025.04.10 |Writing Smart Contracts in Go                                                   |[@leohhhn](https://github.com/leohhhn)                                   |[Slides](presentations/2025-04-10--gnobelgrade--leon/gno-belgrade-04-2025.pdf)                                                              |---                                                                                                  |
 |2025.03.05 |DAOs in gno.land                                                                |[@leohhhn](https://github.com/leohhhn)                                   |[Slides](presentations/2025-03-05--ethbelgrade--leon/ethbelgrade-daos.pdf)                                                                  |[Video](https://www.youtube.com/watch?v=8FJWLKVjbMc)                                                 |
 |2025.02.05 |Building dApps in gno.land                                                      |[@leohhhn](https://github.com/leohhhn)                                   |[Slides](presentations/2025-02-05--epitech--leon/building-dapps.pdf)                                                                        |---                                                                                                  |
 |2025.02.01 |building decentralized apps in go: meet gno                                     |[@moul](https://github.com/moul)                                         |[Slides](https://gnolang.github.io/workshops/presentations/2025-02-01--fosdem--manfred/presentation.slide.html#1)                           |---                                                                                                  |

presentations/2025-04-10--gnobelgrade--leon/gno-belgrade-04-2025.pdf

@@ -0,0 +1,15 @@
+# Date of the workshop
+date: "2025-04-10"
+# Title of the workshop
+title: "Writing Smart Contracts in Go"
+# GitHub usernames of the speakers
+speakers:
+  - "leohhhn"
+# Location of the workshop
+location: "Belgrade, Serbia"
+# At which event the workshop took place, if any
+event: "Gno Belgrade Meetup"
+# Workshop slides link. If the link is local, only put the file name, without any other path parts.
+slides: "gno-belgrade-04-2025.pdf"
+# Workshop recording
+recording: ""