Adds community page for symfonycon amsterdam (#406)

### Description

Adds a community page for Symphony Con Amsterdam conference.

Additional cards may be added at a later date, but conference deadlines
means the page needs to be added ASAP.
 
### Issues Resolved

n/a

### Check List
- [x] Commits are signed per the DCO using `--signoff`

By submitting this pull request, I confirm that my contribution is made
under the terms of the BSD-3-Clause License.

Signed-off-by: Kyle J. Davis <[email protected]>

Author: stockholmux

content/community/symfonycon-ams.md

@@ -0,0 +1,12 @@
++++
+title = "Welcome SymfonyCon Amsterdam 2025"
+description = "Welcome SymfonyCon Amsterdam 2025"
+template = "community.html"
+page_template = "community.html"
+[extra]
+cards = []
++++
+
+# Welcome SymfonyCon Amsterdam 2025
+## How to Contribute with us?
+We welcome your involvement in the Valkey community! Here are several ways you can contribute: