docs: Add axi_clkgen, axi_adc_decimate, axi_adc_trigger, axi_dac_interpolate, axi_fan_control IP Cores

[gastmaier]

PR Description

Cherry-picked from the doc-ips branch

ae62febfd docs: regmap: Add adi_regmap_clkgen.txt 247a2c6ea docs: Add axi_clkgen IP core 65056417b docs: regmap: Add adi_regmap_axi_adc_decimate.txt 0f2b2f7ea docs: Add axi_adc_decimate IP core 7a9bed276 docs: regmap: Add adi_regmap_axi_adc_trigger.txt 2033ec321 docs: Add axi_adc_trigger IP core 054269750 docs: regmap: Add adi_regmap_interpolate.txt cefcb2ce7 docs: Add axi_dac_interpolate IP core 0922c21f0 docs: regmap: Add adi_regmap_fan_control.txt ba730cfdc docs: Add axi_fan_control IP core

These IPs are not owned by anyone.

PR Type

• [ ] Bug fix (change that fixes an issue)
• [ ] New feature (change that adds new functionality)
• [ ] Breaking change (has dependencies in other repos or will cause CI to fail)

PR Checklist

• [ ] I have followed the code style guidelines
• [ ] I have performed a self-review of changes
• [ ] I have compiled all hdl projects and libraries affected by this PR
• [ ] I have tested in hardware affected projects, at least on relevant boards
• [ ] I have commented my code, at least hard-to-understand parts
• [ ] I have signed off all commits from this PR
• [ ] I have updated the documentation (wiki pages, ReadMe files, Copyright etc)
• [ ] I have not introduced new Warnings/Critical Warnings on compilation
• [ ] I have added new hdl testbenches or updated existing ones