chore: improve doc & cleanup

[bigopon]

📖 Description

• some doc improvement
  • add doc for clarifying various binding syntaxes close [Doc] Have doc to clarify the difference among binding usages #1565
  • add doc to clarify how to use development build with bundlers thanks @Sayan751
• relax typescript dev dependency version for plugin-conventions, thanks @3cp
• routing cleanup & maintenance
• prepare failing tests for [RFC] synchronous vs asynchronous binding system for Aurelia 2 #1957

[codecov]

Codecov Report

Attention: Patch coverage is 36.36364% with 14 lines in your changes are missing coverage. Please review.

Project coverage is 88.61%. Comparing base (be8fa67) to head (e21d13f).

Files	Patch %	Lines
packages/router/src/route.ts	50.00%	5 Missing ⚠️
packages/router/src/browser-viewer-store.ts	0.00%	3 Missing ⚠️
packages/router/src/endpoints/viewport-content.ts	0.00%	2 Missing ⚠️
packages/router/src/navigator.ts	0.00%	2 Missing ⚠️
packages/router/src/router.ts	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1983      +/-   ##
==========================================
+ Coverage   88.58%   88.61%   +0.02%     
==========================================
  Files         278      278              
  Lines       22911    22908       -3     
  Branches     5292     5292              
==========================================
+ Hits        20295    20299       +4     
+ Misses       2616     2609       -7     

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