docs: readme installer options and plain wording

The quick install block gains the PowerShell form that passes options and a link to the installer page. The collection size uses the GB format of the download table and the site, counts get separators, and the sentences about RetroArch's existence check and the method describe the code instead of judging documentation.

scripts/generate_readme.py

@@ -329,7 +329,6 @@ def _catalog_matched_line(db: dict) -> list[str]:
 def generate_readme(db: dict, platforms_dir: str) -> str:
     total_files = db.get("total_files", 0)
     total_size = db.get("total_size", 0)
-    size_mb = total_size / (1024 * 1024)
     ts = datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
 
     platform_names = list_registered_platforms(platforms_dir, include_archived=True)
@@ -397,9 +396,13 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
         "# SD card mounted on a PC: --dest is the BIOS folder on the card",
         "# (RetroArch on Switch: retroarch/cores/system, on Android: RetroArch/system)",
         "curl -fsSL https://raw.githubusercontent.com/Abdess/retrobios/main/install.sh | sh -s -- --platform retroarch --dest /path/to/sdcard/retroarch/cores/system",
+        "",
+        "# Options in PowerShell: anything after | iex goes to iex, so the script runs as a block",
+        "&([scriptblock]::Create((irm https://raw.githubusercontent.com/Abdess/retrobios/main/install.ps1))) --check",
         "```",
         "",
         "The script auto-detects your platform, downloads only missing files, and verifies checksums.",
+        f"Every option, and what the installer detects and writes, is on the [installer page]({SITE_URL}wiki/installer/#passing-options).",
         "",
         "## Download BIOS packs",
         "",
@@ -462,16 +465,17 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
             "",
             "Each file is checked the way your platform checks it. Most compare"
             " a checksum, the fingerprint of a file's contents, which catches a"
-            " corrupt or unexpected copy. RetroArch, Lakka and RetroPie only"
-            " look for the filename, because that is all their code does: the"
+            " corrupt or unexpected copy. RetroArch, Lakka and RetroPie check"
+            " that the file is present under its name without reading its"
+            " contents (`path_is_valid` in RetroArch's `core_info.c`): the"
             " Coverage table says which applies to you. Independently of that,"
             " the collection records five fingerprints per file, and wherever"
             " an emulator's code states an expected size or hash, that value is"
             " read from its source and rechecked here.",
             "",
             (
-                f"- **{acquirable_total} files** the platforms' emulators load"
-                f" are still to be found, and {unsourceable_total} more cannot"
+                f"- **{acquirable_total:,} files** the platforms' emulators load"
+                f" are still to be found, and {unsourceable_total:,} more cannot"
                 f" be sourced at all (per-user keys, user-filled slots, dumps"
                 f" nobody has made). Both are named in the"
                 f" [gap analysis]({SITE_URL}gaps/)"
@@ -484,7 +488,7 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
             f"- **{len(system_ids)} systems** handled by those emulators (NES, SNES, PlayStation, Saturn, Dreamcast, ...)",
             collection_line(total_files, comp),
             *_catalog_matched_line(db),
-            f"- **{size_mb:.0f} MB** total collection size",
+            f"- **{format_size(total_size)}** for the whole collection",
             "",
             "## Supported systems",
             "",
@@ -621,10 +625,10 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
             "",
             "## How it works",
             "",
-            "Documentation and metadata can drift from what emulators actually load.",
-            "To keep packs accurate, platform lists are checked against emulator"
-            " source code, file by file where a profile exists. When the two"
-            " disagree, the code wins.",
+            "A platform's BIOS list and an emulator's code are maintained"
+            " separately. Each list is compared with the emulator source code,"
+            " file by file where a profile exists, and where the two differ the"
+            " code decides.",
             "",
             "Hashes document what emulator code loads and accepts, not dump"
             " provenance. That boundary, and how it relates to preservation"

scripts/generate_site.py

@@ -2697,7 +2697,7 @@ def generate_emulators_index(profiles: dict) -> str:
     lines = [
         "# Emulators",
         "",
-        f"**{len(unique)}** emulator profiles, **{total_files}** files total, **{len(aliases)}** aliases.",
+        f"**{len(unique):,}** emulator profiles, **{total_files:,}** files total, **{len(aliases):,}** aliases.",
         "",
         "| Classification | Count | Description |",
         "|---------------|-------|-------------|",