Minor docs correction for SymbolicPulse library (#10161)

* Correct doc string for Sawtooth,Triangle, Cos, Sin

* Added a few missing \

qiskit/pulse/library/symbolic_pulses.py

@@ -1450,7 +1450,7 @@ def Sin(
 
     .. math::
 
-        f(x) &= \\text{A}\\sin\\left(2\\pi\text{freq}x+\\text{phase}\\right)  ,  0 <= x < duration
+        f(x) = \\text{A}\\sin\\left(2\\pi\\text{freq}x+\\text{phase}\\right)  ,  0 <= x < duration
 
     where :math:`\\text{A} = \\text{amp} \\times\\exp\\left(i\\times\\text{angle}\\right)`.
 
@@ -1517,7 +1517,7 @@ def Cos(
 
     .. math::
 
-        f(x) &= \\text{A}\\cos\\left(2\\pi\text{freq}x+\\text{phase}\\right)  ,  0 <= x < duration
+        f(x) = \\text{A}\\cos\\left(2\\pi\\text{freq}x+\\text{phase}\\right)  ,  0 <= x < duration
 
     where :math:`\\text{A} = \\text{amp} \\times\\exp\\left(i\\times\\text{angle}\\right)`.
 
@@ -1584,7 +1584,7 @@ def Sawtooth(
 
     .. math::
 
-        f(x) &= 2\\text{A}\\left[g\\left(x\\right)-
+        f(x) = 2\\text{A}\\left[g\\left(x\\right)-
             \\lfloor g\\left(x\\right)+\\frac{1}{2}\\rfloor\\right]
 
     where :math:`\\text{A} = \\text{amp} \\times\\exp\\left(i\\times\\text{angle}\\right)`,
@@ -1655,7 +1655,7 @@ def Triangle(
 
     .. math::
 
-        f(x) &= \\text{A}\\left[\\text{sawtooth}\\left(x\\right)right]  ,  0 <= x < duration
+        f(x) = \\text{A}\\left[\\text{sawtooth}\\left(x\\right)\\right]  ,  0 <= x < duration
 
     where :math:`\\text{A} = \\text{amp} \\times\\exp\\left(i\\times\\text{angle}\\right)`,
     and :math:`\\text{sawtooth}\\left(x\\right)` is a sawtooth wave with the same frequency