DOC-1064: Update ActiveCampaign credentials to medium tier template

[freakwriter]

Removed prerequisite section, added more detailed numbered steps.

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Overall readability score: 43.11 (🟢 +0.03)

File	Readability
activecampaign.md	56.63 (🟢 +29.92)

View detailed metrics

🟢 - Shows an _increase_ in readability 🔴 - Shows a _decrease_ in readability File | Readability | FRE | GF | ARI | CLI | DCRS --- | --- | --- | --- | --- | --- | --- [activecampaign.md](https://github.com/n8n-io/n8n-docs/blob/0a00286ede3aaa2d7e5bd7675acc2848668525e4/docs/integrations/builtin/credentials/activecampaign.md "docs/integrations/builtin/credentials/activecampaign.md") | 56.63 | 33.41 | 9 | 12.6 | 13.85 | 6.94   | 🟢 +29.92 | 🟢 +31.71 | 🟢 +2.08 | 🟢 +6.3 | 🟢 +5.15 | 🟢 +1.46 Averages:   | Readability | FRE | GF | ARI | CLI | DCRS --- | --- | --- | --- | --- | --- | --- Average | 43.11 | 34.83 | 11.67 | 14.88 | 14.36 | 8.54   | 🟢 +0.03 | 🟢 +0.03 | 🟢 +0 | 🟢 +0.01 | 🟢 +0 | 🟢 +0

View metric targets

Metric | Range | Ideal score --- | --- | --- Flesch Reading Ease | 100 (very easy read) to 0 (extremely difficult read) | 60 Gunning Fog | 6 (very easy read) to 17 (extremely difficult read) | 8 or less Auto. Read. Index | 6 (very easy read) to 14 (extremely difficult read) | 8 or less Coleman Liau Index | 6 (very easy read) to 17 (extremely difficult read) | 8 or less Dale-Chall Readability | 4.9 (very easy read) to 9.9 (extremely difficult read) | 6.9 or less