Minor grammar and filename fixes in docs (#7559)

Grammar in coding_conventions_c.md and coding_conventions_python.md

`rule.mk` to `rules.mk` in feature_haptic_feedback.md and feature_rgb_matrix.md

docs/coding_conventions_c.md

@@ -14,7 +14,7 @@ Most of our style is pretty easy to pick up on, but right now it's not entirely
   * Think of them as a story describing the feature
   * Use them liberally to explain why particular decisions were made.
   * Do not write obvious comments
-  * If you not sure if a comment is obvious, go ahead and include it.
+  * If you're not sure if a comment is obvious, go ahead and include it.
 * In general we don't wrap lines, they can be as long as needed. If you do choose to wrap lines please do not wrap any wider than 76 columns.
 * We use `#pragma once` at the start of header files rather than old-style include guards (`#ifndef THIS_FILE_H`, `#define THIS_FILE_H`, ..., `#endif`)
 * We accept both forms of preprocessor if's: `#ifdef DEFINED` and `#if defined(DEFINED)`

docs/coding_conventions_python.md

@@ -8,7 +8,7 @@ Most of our style follows PEP8 with some local modifications to make things less
   * Think of them as a story describing the feature
   * Use them liberally to explain why particular decisions were made.
   * Do not write obvious comments
-  * If you not sure if a comment is obvious, go ahead and include it.
+  * If you're not sure if a comment is obvious, go ahead and include it.
 * We require useful docstrings for all functions.
 * In general we don't wrap lines, they can be as long as needed. If you do choose to wrap lines please do not wrap any wider than 76 columns.
 * Some of our practices conflict with the wider python community to make our codebase more approachable to non-pythonistas.

docs/feature_haptic_feedback.md

@@ -2,7 +2,7 @@
 
 ## Haptic feedback rules.mk options
 
-The following options are currently available for haptic feedback in `rule.mk`:
+The following options are currently available for haptic feedback in `rules.mk`:
 
 `HAPTIC_ENABLE += DRV2605L`
 

docs/feature_rgb_matrix.md

@@ -286,7 +286,7 @@ You can disable a single effect by defining `DISABLE_[EFFECT_NAME]` in your `con
 
 ## Custom RGB Matrix Effects
 
-By setting `RGB_MATRIX_CUSTOM_USER` (and/or `RGB_MATRIX_CUSTOM_KB`) in `rule.mk`, new effects can be defined directly from userspace, without having to edit any QMK core files.
+By setting `RGB_MATRIX_CUSTOM_USER` (and/or `RGB_MATRIX_CUSTOM_KB`) in `rules.mk`, new effects can be defined directly from userspace, without having to edit any QMK core files.
 
 To declare new effects, create a new `rgb_matrix_user/kb.inc` that looks something like this: