Note skip-ignore for "Skipping node_modules" (#1553)

* Note `skip-ignore` for "Skipping `node_modules`"

* Remove spurious duplication

* update

* revert changes to readme; readme is built from docs/

* more wordsmithing

* more tweaks

Co-authored-by: Andrew Bradley <cspotcode@gmail.com>

website/docs/how-it-works.md

@@ -16,9 +16,16 @@ Vanilla `node` loads `.js` by reading code from disk and executing it.  Our hook
 
 ## Skipping `node_modules`
 
-By default, **TypeScript Node** avoids compiling files in `/node_modules/` for three reasons:
+By default, ts-node avoids compiling files in `/node_modules/` for three reasons:
 
 1. Modules should always be published in a format node.js can consume
 2. Transpiling the entire dependency tree will make your project slower
 3. Differing behaviours between TypeScript and node.js (e.g. ES2015 modules) can result in a project that works until you decide to support a feature natively from node.js
 
+If you need to import uncompiled TypeScript in `node_modules`, use [`--skipIgnore`](./options#transpilation) or [`TS_NODE_SKIP_IGNORE`](./options#transpilation) to bypass this restriction.
+
+## Skipping pre-compiled TypeScript
+
+If a compiled JavaScript file with the same name as a TypeScript file already exists, the TypeScript file will be ignored.  ts-node will import the pre-compiled JavaScript.
+
+To force ts-node to import the TypeScript source, not the precompiled JavaScript, use [`--preferTsExts`](./options#transpilation).