Update the formulas for Tee and Pi Attenuators

This makes clear that we are utilizing the voltage attenuation formula while keeping the correct formulation as it is implemented in the code

Fixes https://gitlab.com/kicad/code/kicad/-/issues/12659

pcb_calculator/attenuators/pi_formula.h

@@ -4,7 +4,8 @@ _HKI( "### Pi Attenuator\n"
 "___Z<sub>in</sub>___ is desired input impedance in &#x2126;<br>\n"
 "___Z<sub>out</sub>___ is desired output impedance in &#x2126;<br>\n"
 "\n"
-"___L = 10<sup>a/20</sup>___<br>\n"
+"___K = V<sub>I</sub>/V<sub>O</sub> = 10<sup>a/20</sup>___<br>\n"
+"___L = K<sup>2</sup> = 10<sup>a/10</sup>___<br>\n"
 "___A = (L+1) / (L&minus;1)___<br><br>\n"
 "___R2 = (L&minus;1) / 2&middot;&radic;(Z<sub>in</sub> &middot; Z<sub>out</sub> / L)___<br>\n"
 "___R1 = 1 / (A/Z<sub>in</sub> &minus; 1/R2)___<br>\n"

pcb_calculator/attenuators/pi_formula.md

@@ -3,7 +3,8 @@ ___a___ is attenuation in dB<br>
 ___Z<sub>in</sub>___ is desired input impedance in &#x2126;<br>
 ___Z<sub>out</sub>___ is desired output impedance in &#x2126;<br>
 
-___L = 10<sup>a/20</sup>___<br>
+___K = V<sub>I</sub>/V<sub>O</sub> = 10<sup>a/20</sup>___<br>
+___L = K<sup>2</sup> = 10<sup>a/10</sup>___<br>
 ___A = (L+1) / (L&minus;1)___<br><br>
 ___R2 = (L&minus;1) / 2&middot;&radic;(Z<sub>in</sub> &middot; Z<sub>out</sub> / L)___<br>
 ___R1 = 1 / (A/Z<sub>in</sub> &minus; 1/R2)___<br>

pcb_calculator/attenuators/tee_formula.h

@@ -4,7 +4,8 @@ _HKI( "### Tee Attenuator\n"
 "___Z<sub>in</sub>___ is desired input impedance in &#x2126;<br>\n"
 "___Z<sub>out</sub>___ is desired output impedance in &#x2126;<br>\n"
 "\n"
-"___L = 10<sup>a/20</sup>___<br>\n"
+"___K = V<sub>I</sub>/V<sub>O</sub> = 10<sup>a/20</sup>___<br>\n"
+"___L = K<sup>2</sup> = 10<sup>a/10</sup>___<br>\n"
 "___A = (L+1) / (L&minus;1)___<br><br>\n"
 "___R2 = 2&middot;&radic;(L &middot; Z<sub>in</sub> &middot; Z<sub>out</sub>) / (L&minus;1)___<br>\n"
 "___R1 = Z<sub>in</sub> &middot; A &minus; R2___<br>\n"

pcb_calculator/attenuators/tee_formula.md

@@ -3,7 +3,8 @@ ___a___ is attenuation in dB<br>
 ___Z<sub>in</sub>___ is desired input impedance in &#x2126;<br>
 ___Z<sub>out</sub>___ is desired output impedance in &#x2126;<br>
 
-___L = 10<sup>a/20</sup>___<br>
+___K = V<sub>I</sub>/V<sub>O</sub> = 10<sup>a/20</sup>___<br>
+___L = K<sup>2</sup> = 10<sup>a/10</sup>___<br>
 ___A = (L+1) / (L&minus;1)___<br><br>
 ___R2 = 2&middot;&radic;(L &middot; Z<sub>in</sub> &middot; Z<sub>out</sub>) / (L&minus;1)___<br>
 ___R1 = Z<sub>in</sub> &middot; A &minus; R2___<br>