docs: Fix broken links

Author: the-spyke

docs/concepts.md

@@ -31,7 +31,7 @@ const pipeline = [
 const iterable = pullLine(pipeline, source);
 ```
 
-Read more about [pull](pull/overview).
+Read more about [pull](docs/pull/overview).
 
 ### Push
 
@@ -53,4 +53,4 @@ const observer = pushLine(pipeline, target);
 
 Of course, you can process synchronous items with `Push Lines` too, but `Pull Lines` are easier to operate and write operations for.
 
-Read more about [push](push/overview).
+Read more about [push](docs/push/overview).

docs/introduction.md

@@ -35,9 +35,9 @@ console.log(result); // [8, 10, 14]
 
 There are 3 main packages:
 
-- [@undercut/pull](pull/overview) -- Pull Lines (Iterables).
-- [@undercut/push](push/overview) -- Push Lines (Observers).
-- [@undercut/utils](utils/overview) -- Various JavaScript language utilities.
+- [@undercut/pull](docs/pull/overview) -- Pull Lines (Iterables).
+- [@undercut/push](docs/push/overview) -- Push Lines (Observers).
+- [@undercut/utils](docs/utils/overview) -- Various JavaScript language utilities.
 
 These packages are the intended way to use `Undercut` and carry `stable ES Next` code in the `ESM` format. It is very convenient for apps using Webpack/Babel/etc, and helps to avoid double compilation and deoptimization. Only [finished proposals (Stage 4)](https://github.com/tc39/proposals/blob/master/finished-proposals.md) may be used in their codebase. The code itself is universal and may be used in Node/Browser/Microwave. Your environment may require `core-js@3` or similar polyfill to use them raw.
 
@@ -53,11 +53,11 @@ yarn add @undercut/pull
 
 ### Additional packages
 
-Several [precompiled packages](precompiled) are available too:
+Several [precompiled packages](docs/packages) are available too:
 
-- [@undercut/cli](cli/overview) -- A command line interface for processing data with JavaScript and `Undercut` in a shell. Accepts string items from `stdin` and puts results as strings into `stdout`. Works on Node.js 10.13 and upwards.
-- [@undercut/node-10](packages#undercutnode-10) -- A precompiled CommonJS version for Node.js 10.13 and upwards. Requires stable polyfills from `core-js@3`.
-- [@undercut/web-2019](packages#undercutweb-2019) -- A precompiled version for web browsers not older than `2019-01-01`. Creates `undercut` variable in the global scope, may also be used by CJS/AMD loaders. Requires stable polyfills from `core-js@3`.
+- [@undercut/cli](docs/cli/overview) -- A command line interface for processing data with JavaScript and `Undercut` in a shell. Accepts string items from `stdin` and puts results as strings into `stdout`. Works on Node.js 10.13 and upwards.
+- [@undercut/node-10](docs/packages#undercutnode-10) -- A precompiled CommonJS version for Node.js 10.13 and upwards. Requires stable polyfills from `core-js@3`.
+- [@undercut/web-2019](docs/packages#undercutweb-2019) -- A precompiled version for web browsers not older than `2019-01-01`. Creates `undercut` variable in the global scope, may also be used by CJS/AMD loaders. Requires stable polyfills from `core-js@3`.
 
 ### Updating
 

docs/packages.md

@@ -12,7 +12,7 @@ Hello world!
 A very long string...
 ```
 
-[Full documentation.](cli/overview)
+[Full documentation.](docs/cli/overview)
 
 ### `@undercut/node-10`
 

docs/push/tutorials.md

@@ -45,4 +45,4 @@ console.log(result); // [1, 4, 9]
 10. You will get here in case of both cancellation and `end-of-sequence` signal.
 11. It is a good place to clean up your resources. You must also signal remaining observers in the chain by calling `observer.return()`.
 
-In case more advanced operations like grouping, where you need to look at all available items first before you can proceed, you can do this in `finally`. Make yourself a flag to skip computation in case of catching a cancellation, and pass items before closing the observer ([see the groupBy operation](packages/undercut-push/src/operations/group_by.js)).
+In case more advanced operations like grouping, where you need to look at all available items first before you can proceed, you can do this in `finally`. Make yourself a flag to skip computation in case of catching a cancellation, and pass items before closing the observer ([see the groupBy operation](https://github.com/the-spyke/undercut/tree/master/packages/undercut-push/src/operations/group_by.js)).