chore(docs): Add error info about libc++ and contextual search (#4328)

# Description

- Adds contextual search to the docs (so it will always search within
the selected version).
- Adds a note about installing libc++-dev when getting the associated
backend error. I added to the migration notes page instead of the
installation page because people will hit this when they run `nargo
prove`. There are other messages about backend errors on that page, so
it seemed like a more appropriate place.

Check one:
- [ ] No documentation needed.
- [x] Documentation included in this PR.
- [ ] **[Exceptional Case]** Documentation to be submitted in a separate
PR.

# PR Checklist\*

- [ ] I have tested the changes locally.
- [ ] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

---------

Co-authored-by: Tom French <[email protected]>
Co-authored-by: Savio <[email protected]>

cspell.json

@@ -38,6 +38,7 @@
         "codegen",
         "codegenned",
         "codegens",
+        "codespace",
         "Codespaces",
         "codespan",
         "coeff",
@@ -100,6 +101,7 @@
         "keccak",
         "keccakf",
         "krate",
+        "libc",
         "losslessly",
         "lvalue",
         "Maddiaa",

docs/docs/migration_notes.md

@@ -6,6 +6,20 @@ keywords: [Noir, notes, migration, updating, upgrading]
 
 Noir is in full-speed development. Things break fast, wild, and often. This page attempts to leave some notes on errors you might encounter when upgrading and how to resolve them until proper patches are built.
 
+### `backend encountered an error: libc++.so.1`
+
+Depending on your OS, you may encounter the following error when running `nargo prove` for the first time:
+
+```text
+The backend encountered an error: "/home/codespace/.nargo/backends/acvm-backend-barretenberg/backend_binary: error while loading shared libraries: libc++.so.1: cannot open shared object file: No such file or directory\n"
+```
+
+Install the `libc++-dev` library with:
+
+```bash
+sudo apt install libc++-dev
+```
+
 ## ≥0.19
 
 ### Enforcing `compiler_version`

docs/docusaurus.config.ts

@@ -133,7 +133,7 @@ export default {
 
       // Public API key: it is safe to commit it
       apiKey: 'b9b94d2f1c58f7d509f0bc1f13b381fb',
-
+      contextualSearch: true,
       indexName: 'noir-lang',
     },
   },

docs/versioned_docs/version-v0.22.0/migration_notes.md

@@ -6,6 +6,20 @@ keywords: [Noir, notes, migration, updating, upgrading]
 
 Noir is in full-speed development. Things break fast, wild, and often. This page attempts to leave some notes on errors you might encounter when upgrading and how to resolve them until proper patches are built.
 
+### `backend encountered an error: libc++.so.1`
+
+Depending on your OS, you may encounter the following error when running `nargo prove` for the first time:
+
+```text
+The backend encountered an error: "/home/codespace/.nargo/backends/acvm-backend-barretenberg/backend_binary: error while loading shared libraries: libc++.so.1: cannot open shared object file: No such file or directory\n"
+```
+
+Install the `libc++-dev` library with:
+
+```bash
+sudo apt install libc++-dev
+```
+
 ## ≥0.19
 
 ### Enforcing `compiler_version`

docs/versioned_docs/version-v0.23.0/migration_notes.md

@@ -6,6 +6,22 @@ keywords: [Noir, notes, migration, updating, upgrading]
 
 Noir is in full-speed development. Things break fast, wild, and often. This page attempts to leave some notes on errors you might encounter when upgrading and how to resolve them until proper patches are built.
 
+## 0.22.0
+
+### `backend encountered an error: libc++.so.1`
+
+Depending on your OS, you may encounter the following error when running `nargo prove` for the first time:
+
+```text
+The backend encountered an error: "/home/codespace/.nargo/backends/acvm-backend-barretenberg/backend_binary: error while loading shared libraries: libc++.so.1: cannot open shared object file: No such file or directory\n"
+```
+
+Install the `libc++-dev` library with:
+
+```bash
+sudo apt install libc++-dev
+```
+
 ## ≥0.19
 
 ### Enforcing `compiler_version`