Docs via make (#124)

## What Changed?

Simplifies the doc setup by performing the necessary steps via
cargo-make

## Why Does It Need To?

Describe the concern this change addresses. 

The program in `doc-src` is no longer necessary.

## Checklist

- [x] Above description has been filled out so that upon quash merge we
have a
  good record of what changed.
- [x] New functions, methods, types are documented. Old documentation is
updated
  if necessary
- [x] Documentation in Notion has been updated
- [x] Tests for new behaviors are provided
  - [x] New test suites (if any) ave been added to the CI tests (in
`.github/workflows/rust.yml`) either as compiler test or integration
test.
*Or* justification for their omission from CI has been provided in this
PR
    description.

.github/workflows/docs.yml

@@ -21,17 +21,19 @@ jobs:
       run: |
         git config --local user.email "docmaster+github-actions[bot]@users.noreply.github.com"
         git config --local user.name "github-actions[bot]"
+    - name: Install cargo-make
+      uses: actions-rs/cargo@v1
+      with:
+        command: install
+        args: --debug cargo-make
     - name: Prepare
       run: |
         cargo doc --document-private-items
         mkdir docs
         cp -R target/doc docs/libs
         rm -R .github
-    - name: Copy Rustc Docs
-      run: cargo run
-      working-directory: doc-src
-    - name: Copy index page
-      run: cp doc-src/index.html docs/index.html
+    - name: Copy rustc docs and index page
+      run: cargo make populate-doc-dir
     - name: Commit Doc Generation
       run: |
         git add docs

Makefile.toml

@@ -203,3 +203,17 @@ end
 cd crates/paralegal-policy/tests/test-crate
 exec cargo %{FORMAT_ARGS}
 '''
+
+[tasks.populate-doc-dir]
+dependencies = ["get-rustc-docs"]
+script_runner = "@duckscript"
+script = '''
+source_path = concat ${RUSTUP_HOME} /toolchains/ ${RUSTUP_TOOLCHAIN} /share/doc/rust/html/rustc
+mkdir docs
+mv doc-src/index.html docs
+mv ${source_path} docs/compiler
+'''
+
+[tasks.get-rustc-docs]
+command = "rustup"
+args = ["component", "add", "rustc-docs"]