Fix(docs): add await to the integration examples in the documentation

[ickynavigator]

Changed the docs integration examples to use the await since render now returns a Promise<string> and not a string. There are still some more changes that need to be made in the examples/[INTEGRATION] folder but for some reason my pnpm and the one on codespaces is unable to complete the pnpm install command

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[gabrielmfern]

Thanks for this! Will fix the missing await on the examples

[ickynavigator]

you're welcome!!

btw this is the error i got when i tried to install and work on the examples

~/ghq/github.com/resend/react-email
❯ ni
Scope: all 31 workspace projects
Lockfile is up to date, resolution step is skipped
Already up to date
 WARN  Failed to create bin at /Users/fortuneobi/ghq/github.com/resend/react-email/apps/demo/node_modules/.bin/email. ENOENT: no such file or directory, open '/Users/fortuneobi/ghq/github.com/resend/react-email/packages/react-email/dist/cli/index.js'
 WARN  Failed to create bin at /Users/fortuneobi/ghq/github.com/resend/react-email/apps/web/node_modules/.bin/email. ENOENT: no such file or directory, open '/Users/fortuneobi/ghq/github.com/resend/react-email/packages/react-email/dist/cli/index.js'
 WARN  Failed to create bin at /Users/fortuneobi/ghq/github.com/resend/react-email/benchmarks/preview-server/node_modules/.bin/email. ENOENT: no such file or directory, open '/Users/fortuneobi/ghq/github.com/resend/react-email/packages/react-email/dist/cli/index.js'
 WARN  Failed to create bin at /Users/fortuneobi/ghq/github.com/resend/react-email/packages/create-email/template/node_modules/.bin/email. ENOENT: no such file or directory, open '/Users/fortuneobi/ghq/github.com/resend/react-email/packages/react-email/dist/cli/index.js'
 WARN  Failed to create bin at /Users/fortuneobi/ghq/github.com/resend/react-email/benchmarks/preview-server/node_modules/.bin/email. ENOENT: no such file or directory, open '/Users/fortuneobi/ghq/github.com/resend/react-email/benchmarks/preview-server/node_modules/react-email/dist/cli/index.js'
 WARN  3 other warnings
Done in 1.5s