Manual installation guide has a couple of rough edges

[h14h]

In testing out some SDK 52 issues, I noticed a couple minor rough edges in the manual installation instructions:

1. The example files use the ~ alias without instructing folks to add it in their tsconfig.json
2. The guide's Text component is out of date with the current version, and missing react-native-uitextview as a dependency
   • If you later install another component that depends on Text (e.g. Button) via the CLI, and allow it to replace Text, it doesn't install react-native-uitextview

Neither of these is a deal-breaker, but could trip up a beginner.

I can try to set aside some time for a PR if y'all have other priorities.

[h14h]

I can't find the source for the docs, so I'm not sure I'll be able to create a PR to address this.