Docs: add text formatting rules

[imatwawana]

Adds guidance for formatting abstract UI concepts and bold formatting in tables

[github-actions[bot]]

Readability report

File	AutomatedReadability	ColemanLiau	FleschKincaid	FleschReadingEase	GunningFog	LIX	SMOG
docs/sources/write/style-guide/capitalization-punctuation/index.md	$${8.75\space\color{red}(Δ+0.02)}$$	$${11.87\space\color{green}(Δ-0.06)}$$	$${9.30\space\color{red}(Δ+0.03)}$$	$${49.93\space\color{green}(Δ+0.09)}$$	$${10.65\space\color{red}(Δ+0.01)}$$	$${41.16\space\color{green}(Δ-0.11)}$$	$${12.07\space\color{red}(Δ+0.04)}$$
docs/sources/write/style-guide/style-conventions/index.md	$${7.51\space\color{red}(Δ+0.04)}$$	$${10.34\space\color{green}(Δ-0.09)}$$	$${8.36\space\color{red}(Δ+0.07)}$$	$${56.66\space\color{green}(Δ+0.11)}$$	$${10.26\space\color{red}(Δ+0.03)}$$	$${38.70\space\color{green}(Δ-0.16)}$$	$${11.24\space\color{red}(Δ+0.05)}$$

View metric targets

| Metric | Range | Ideal score | | --- | --- | --- | | [AutomatedReadability](https://en.wikipedia.org/wiki/Automated_readability_index) | 6 (very easy read) to 14 (extremely difficult read) | 8 or less | | [ColemanLiau](https://en.wikipedia.org/wiki/Coleman%E2%80%93Liau_index) | 6 (very easy read) to 17 (extremely difficult read) | 9 or less | | [FleschKincaid](https://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_tests) | 6 (very easy read) to 17 (extremely difficult read) | 8 or less | | [FleschReadingEase](https://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_tests) | 100 (very easy read) to 0 (extremely difficult read) | 70 or more | | [GunningFog](https://en.wikipedia.org/wiki/Gunning_fog_index) | 6 (very easy read) to 17 (extremely difficult read) | 10 or less | | [LIX](https://en.wikipedia.org/wiki/Lix_(readability_test)) | 20 (very easy read) to 60+ (extremely difficult read) | 35 or less | | [SMOG](https://en.wikipedia.org/wiki/SMOG) | 6 (very easy read) to 17 (extremely difficult read) | 10 or less |