docs: update README with fix for installing context7 in the Windows Codex

[kv-chiu]

Summary

This PR supplements the fix for installing context7 in the Windows Codex.

Root Cause

Codex MCP clients clear the environment and only pass a small whitelist on Windows, which often excludes APPDATA and SystemRoot. This breaks npx/npm resolution and causes timeouts.

Refer to openai/codex#4180

/// codex 0.46.0
/// codex-rs/mcp-client/src/mcp_client.rs:435
#[cfg(windows)]
const DEFAULT_ENV_VARS: &[&str] = &[
    // TODO: More research is necessary to curate this list.
    "PATH",
    "PATHEXT",
    "USERNAME",
    "USERDOMAIN",
    "USERPROFILE",
    "TEMP",
    "TMP",
];

/// Missing APPDATA, resulting “request timed out” in npm/npx based servers

Fixes #575 #658

[enesgules]

Wow, it's crazy how big this section got
Could you use details and summary tags for the errors so that when most users who don't encounter errors don't see the long error related texts immediately unless they search for it

[kv-chiu]

Wow, it's crazy how big this section got Could you use details and summary tags for the errors so that when most users who don't encounter errors don't see the long error related texts immediately unless they search for it

Ok

[kv-chiu]

Wow, it's crazy how big this section got Could you use details and summary tags for the errors so that when most users who don't encounter errors don't see the long error related texts immediately unless they search for it

I tried using details and summary, but the nested structure wasn't very readable. So I kept the core corrective approach and simplified potentially repetitive content, and clearly distinguished from the default configuration.

[kv-chiu]

before:

after:

[enesgules]

TYSM!