Add new Polymarket documentation (2026-02-17)

- Added 31 new documentation pages from llms.txt index
- Updated changelog and 4 existing pages
- New categories: polymarket-learn (FAQ, deposits, get-started, markets, trading)
- New API: get-positions-for-a-market
- New guide: builders examples

docs/polymarket-learn/FAQ/support.md

@@ -0,0 +1,23 @@
+> ## Documentation Index
+> Fetch the complete documentation index at: https://docs.polymarket.com/llms.txt
+> Use this file to discover all available pages before exploring further.
+
+# How Do I Contact Support?
+
+> Polymarket offers technical support through our website chat feature, and through Discord.
+
+To contact support through our website:
+
+* Navigate to [Polymarket](https://polymarket.com).
+
+* Click the blue chat icon in the bottom right and start your chat session.
+
+For technical support on Discord:
+
+* Join the [Polymarket Discord server](https://discord.gg/polymarket)
+
+* Navigate to the Support sidebar and click #open-a-ticket. This will open a private conversation with a Polymarket team member.
+
+<Warning>
+  Be aware of numerous scams and malicious links. Polymarket team members will never DM you first or ask for private keys or personal information. Polymarket team members are identified in blue font on Discord.
+</Warning>