I am dumb and can't spell (#1366)

* rename implementor's guide to implementer's guide

* fix typos in more places

polkadot/roadmap/implementers-guide/src/SUMMARY.md

@@ -0,0 +1,51 @@
+# Summary
+
+[Preamble](README.md)
+
+- [Whence Parachains](whence-parachains.md)
+- [Parachains Overview](parachains-overview.md)
+- [Architecture Overview](architecture.md)
+- [Runtime Architecture](runtime/README.md)
+  - [Initializer Module](runtime/initializer.md)
+  - [Configuration Module](runtime/configuration.md)
+  - [Paras Module](runtime/paras.md)
+  - [Scheduler Module](runtime/scheduler.md)
+  - [Inclusion Module](runtime/inclusion.md)
+  - [InclusionInherent Module](runtime/inclusioninherent.md)
+  - [Validity Module](runtime/validity.md)
+  - [Router Module](runtime/router.md)
+- [Node Architecture](node/README.md)
+  - [Subsystems and Jobs](node/subsystems-and-jobs.md)
+  - [Overseer](node/overseer.md)
+  - [Backing Subsystems](node/backing/README.md)
+    - [Candidate Selection](node/backing/candidate-selection.md)
+    - [Candidate Backing](node/backing/candidate-backing.md)
+    - [Statement Distribution](node/backing/statement-distribution.md)
+    - [PoV Distribution](node/backing/pov-distribution.md)
+  - [Availability Subsystems](node/availability/README.md)
+    - [Availability Distribution](node/availability/availability-distribution.md)
+    - [Bitfield Distribution](node/availability/bitfield-distribution.md)
+    - [Bitfield Signing](node/availability/bitfield-signing.md)
+  - [Collators](node/collators/README.md)
+    - [Collation Generation](node/collators/collation-generation.md)
+    - [Collation Distribution](node/collators/collation-distribution.md)
+  - [Validity](node/validity/README.md)
+  - [Utility Subsystems](node/utility/README.md)
+    - [Availability Store](node/utility/availability-store.md)
+    - [Candidate Validation](node/utility/candidate-validation.md)
+    - [Provisioner](node/utility/provisioner.md)
+    - [Network Bridge](node/utility/network-bridge.md)
+    - [Misbehavior Arbitration](node/utility/misbehavior-arbitration.md)
+    - [Peer Set Manager](node/utility/peer-set-manager.md)
+    - [Runtime API Requests](node/utility/runtime-api.md)
+- [Data Structures and Types](types/README.md)
+    - [Candidate](types/candidate.md)
+    - [Backing](types/backing.md)
+    - [Availability](types/availability.md)
+    - [Overseer and Subsystem Protocol](types/overseer-protocol.md)
+    - [Runtime](types/runtime.md)
+    - [Chain](types/chain.md)
+    - [Messages](types/messages.md)
+
+[Glossary](glossary.md)
+[Further Reading](further-reading.md)