docs: fix formatting in Good First Issue guidelines (hiero-ledger#1831)

Signed-off-by: OmaarSaaleh <omaarsaaleh1@gmail.com>

Author: omaarsaaleh

CHANGELOG.md

@@ -19,6 +19,7 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 - Refactored contract_delete_transaction example to use Client.from_env. (#1823)
 
 ### Docs
+- Fixed Test Improvements header formatting in Good First Issue guidelines by adding missing space before parenthetical and removing stray bold marker (#1829)
 - Improved Google-style docstring for `compress_point_unchecked` in `crypto_utils.py`. (#1625)
 - chore: update office hours and community calls to use direct links (`#1804`)
 

docs/maintainers/good_first_issues_guidelines.md

@@ -97,7 +97,7 @@ The following are good fits for Good First Issues **when the solution is explici
 > ⚠️ In most cases, changes to `src` functionality are **not** Good First Issues.  
 > This category applies only when the change is **purely mechanical and fully specified**.
 
-### Suitable for Good First Issues (rare, explicit cases only):**
+### Suitable for Good First Issues (rare, explicit cases only):
 - Very small, explicitly described edits to existing code  
 - Changes that do not require understanding how the code is used elsewhere  
 
@@ -145,7 +145,7 @@ Documentation tasks must be **explicitly scoped and instruction-driven**.
 
 > ⚠️ Most test-related work is better suited for **Beginner or Intermediate Issues**.
 
-### Suitable for Good First Issues(rare, explicit cases only):**
+### Suitable for Good First Issues (rare, explicit cases only):
 - Adding a clearly specified assertion to an existing test  
 - Small mechanical edits with no test-design decisions