Remove /docs slash command (#36325)

This PR removes the `/docs` slash command.

We never fully shipped this—with it requiring explicit opt-in via a
setting—and it doesn't seem like the feature is needed in an agentic
world.

Release Notes:

- Removed the `/docs` slash command.

Cargo.lock

@@ -347,7 +347,6 @@ dependencies = [
  "gpui",
  "html_to_markdown",
  "http_client",
- "indexed_docs",
  "indoc",
  "inventory",
  "itertools 0.14.0",
@@ -872,7 +871,6 @@ dependencies = [
  "gpui",
  "html_to_markdown",
  "http_client",
- "indexed_docs",
  "language",
  "pretty_assertions",
  "project",
@@ -8383,34 +8381,6 @@ version = "1.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d0263a3d970d5c054ed9312c0057b4f3bde9c0b33836d3637361d4a9e6e7a408"
 
-[[package]]
-name = "indexed_docs"
-version = "0.1.0"
-dependencies = [
- "anyhow",
- "async-trait",
- "cargo_metadata",
- "collections",
- "derive_more 0.99.19",
- "extension",
- "fs",
- "futures 0.3.31",
- "fuzzy",
- "gpui",
- "heed",
- "html_to_markdown",
- "http_client",
- "indexmap",
- "indoc",
- "parking_lot",
- "paths",
- "pretty_assertions",
- "serde",
- "strum 0.27.1",
- "util",
- "workspace-hack",
-]
-
 [[package]]
 name = "indexmap"
 version = "2.9.0"