adds QCon SF landing page (#412)

### Description

Adds landing page for QCon SF.

 
### 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 <kyledvs@amazon.com>
Signed-off-by: Madelyn Olson <madelyneolson@gmail.com>
Co-authored-by: Madelyn Olson <madelyneolson@gmail.com>

Author: stockholmux

content/community/qcon-2025.md

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